C^MWO^ 


Columbia  ^ntbtr)s:ttp(^o^y  ( 


iA^Uxma  ©brarg 


THE 


INTKRNAL  ANATOMY 
OF  THE  PACK 


BY 

M.  H.  CRYER,  M.D.,  D.D.S. 

PROFESSOR    OF    ORAL    SURGERY,    UNIVERSITY   OF    PEN'NSYLVANIA ;    ORAL    SURGEON    TO    THE 
PHILADELPHIA  GENERAL  HOSPITAL 


SECOND  EDITION,  REVISED   AND  ENLARGED 


ILLUSTRATED  WITH    377   ENGRAVINGS 


LEA   &   FEBIGER 

PHILADELPHIA    AND    NEW   YORK 
I  g  I  6 


Entered  accordii^  to  the  Act  of  Congress,  in  the  year  1916,  by 

LEA   &  FEBIGER. 
in  the  Office  of  the  Librarian  of  Coi^ress.     All'rights  reserved. 


r\' 


THIS   BOOK 
IS 

AFFECTIONATELY   DEDICATED   TO    MY   WIFE 

MARTHA   GATES   CRYER 


PREFACE  TO  THE  SECOND  EDITION. 


Many  years  ago  the  author  began  to  investigate  the  variations 
from  the  standard  typical  anatomy  of  the  text-books  which  constantly 
presented  themsehes  in  his  surgical  practice.  During  the  past  twenty 
years  hundreds  of  skulls  have  been  sectionized  and  studied.  This 
investigation  completely  overturned  the  author's  conception  of  what 
was  meant  by  the  term  typical.  There  is,  doubtless,  a  typical  or  typal 
form  for  each  bone,  but  it  is  not  often  found  in  nature.  If  we  were  to 
photograph  a  thousand  temporal  bones,  for  example,  and  make  a 
composite  of  the  entire  number,  the  composite  would  properly  be 
accepted  as  figuring  the  typal  temporal.  It  is  possible,  though 
doubtful,  that  of  the  thousand  bones,  two  or  three  could  be  found 
which  would  exactly  correspond  with  the  typal  bone  so  pictured.  This, 
in  the  writer's  view,  is  strong  testimony  that  the  typal  bone  is  ideal; 
that  the  actual  is  a  \'ariant.  It  is  with  these  variants  that  the  surgeon 
and  dentist  have  practically  to  deal. 

The  author's  investigations  of  the  anatomy  of  the  head  have 
convinced  him  of  the  need  for  similar  systematic  study  of  the  ana- 
tomical structure  of  the  other  parts  of  the  body.  For  it  can  scarcely 
be  doubted  that  the  departures  from  the  normal  noted  in  the  bon\- 
structures  of  the  head  and  face  will  be  found  associated  with  equal 
variations  of  the  other  structures.  It  further  shows  that  the  text-l)ook 
by  itself  is  insufficient  for  the  thorough  study  of  anatomy;  that  the 
only  authentic  book  of  anatomy  is  the  body  itself;  that,  therefore, 
the  use  of  text-books  must  be  supplemented  by  the  intimate  stud\- 
of  the  body. 

In  the  preparation  of  this  edition  the  text  has  been  thoroughly 
and  carefully  revised  to  meet  the  requirements  of  those  making  special 
studies   upon,  or  operating    in,   the  region  of    which    it   treats.     New 


vi  PREFACE  TO  THE  SECOND  EDITION 

matter  has  been  added  to  the  extent  of  about  i8o  pages,  including 
chapters  on  the  teeth  with  their  nerve  and  blood  supply;  on  the  dis- 
tribution of  the  trigeminal  nerve;  on  the  uses  of  frozen  sections;  on 
the  inter-relations  between  the  nasal  cavity  and  its  accessory  sinuses 
and  cells.  Wide  and  narrow  dental  arches  have  been  further  considered, 
and  an  extended  chapter  has  been  added  in  which  impacted  teeth, 
modern,  ancient  and  prehistoric  skulls  and  teeth  have  been  compared 
and  noted.  With  certain  modifications  the  Basle  nomenclature  has  been 
generally  adopted. 

The  writer  desires  to  acknowledge  the  encouragement  and  assist- 
ance received  from  Dr.  Thomas  C.  Stellwagen,  Dr.  Edward  C,  Kirk, 
Dr.  Arthur  Hopewell-Smith,  Dr.  Herman  Prinz,  Dr.  Rodrigues 
Ottolengin,  Dr.  Truman  W.  Brophy,  Dr.  Robert  H.  Ivy,  Dr.  A.  H. 
Ketcham,  Dr.  James  D.  McCoy,  and  many  others  who  have  kindly 
furnished  specimens  or  other  material  which  have  aided  so  materially 
in  the  preparation  of  this  volume. 

Matthew  H.  Cryer. 

Philadelphia,   1916. 


CONTENTS. 


CHAPTER    I. 
Introductory 


17 


CHAPTER    H. 
General  Considerations 


Development  of  the  Face 


20 
21 


CHAPTER    HI. 

The  Mandible  or  Lower  Jaw 
Inflammatory  Changes 
Necrosis  and  Regeneration  . 
Fractures  of  the  Mandible 

Neuralgia 

Secondary  Deposits 

IVIandibular  Triangle 

The  Mandibular  Articulation 


23 
48 
49 
59 
64 
64 
67 
68 


CHAPTER    IV. 

The  Maxilla 76 

Studies  of  Certain  External  Surfaces  of  the  Skull 81 

General  Comparisons  between  the  Width  of  the  Upper  Dental  Arch,  the  Floor  of 

THE  Nasal  Fossa,  and  the  Size  of  the  Maxillary  Sinus 94 

CHAPTER   V. 

The  Mouth 100 

The  Teeth 101 

ICruption  of  Teeth 118 

Various  L.lustrations  of  Jaws  and  Teeth 120 

The  Vascular  Supply  of  the  Teeth 134 

The  Sensory  Nerve  Supply  of  the  Teeth  and  Face 139 

Sympathetic  Ganglia  Connected  with  the  Trigeminal  Nerve 154 

Local  Anesthesia  of  the  Teeth,  Surrounding  Tissue,  and  Parts  of  the  Face  Pre- 
sided over  by  the  Trigeminal  Nerve 163 


viii  COX  TEXTS 

CHAPTER  VI. 

Teeth  Influenced  by  Irregular  Eruption 166 

Retarded  Eruption  or  Impacted  Teeth 166 

Supernumerary  Teeth 173 

CHAPTER   VII. 

The  Xasal  Cavity  and  its  Accessory  Cells  and  Sinuses   ....     196 
Pathological  Condition  of  the  Nasal  Cavity         208 

CHAPTER    VIII. 
The  Maxillary  Sinus 217 

CHAPTER    IX. 
The  Frontal  Sinus 248 

CHAPTER   X. 

The  Ethmoid.\l  and  other  Cells  which  have  Their  Final  Outlet  in  the  Nasal  Cavity  259 

The  Orbit.\l  Processes 260 

The  Sphenoid.\l  Sinuses 260 

Cell  of  the  Crista  Galli 262 

CHAPTER   XI. 
Variations  in  the  Anatomical  Structures  of  the  Face    ....     263 

CHAPTER   XII. 
The  Relation  between  the  Mouth,  Tongue,  Pharynx,  and  Nasal  Chamber  .     285 

CHAPTER   XIII. 

MODIFIC.VTION    OF    THE    NORMAL    ShAPE    OF    THE    BONE    THROUGH    ABNORMAL    FoRCES   .       304 

Supernu.merary  Premolar  Teeth 323 

CHAPTER   XIV. 
The  Influence  of  Muscular  Action 330 

CHAPTER   XV. 
Hypertrophy  of  the  Gums  and  Alveolar  Process 342 

CHAPTER   XVI. 
The  Relation  of  the  Two  Jaws 345 


THE  IXTHRXAL  ANATOMY  01-  Till-  FACR. 


CHAPTER   I. 
INTRODUCTORY. 

Carefully  conducted  studies  of  numerous  dissections  prove  con- 
clusively that  many  of  the  stereotyped  descriptions  of  the  internal 
anatomy  of  the  face  are  not  justified  by  the  facts;  and  that,  therefore, 
the  hard  and  fast  rules  for  surgical  procedures  founded  on  these 
descriptions  do  not  adequately  cover  the  ground.  In  pursuance  of 
these  studies,  hundreds  of  sections  of  the  facial  region  have  been  cut 
and  examined.  The  lesson  they  teach  is  that  the  accepted  descrip- 
tions are  to  be  received  as  only  general  truths,  and  that  the>'  cannot 
be  depended  upon  or  followed  literally  as  a  guide  for  the  surgeon  or 
dentist.  The  results  of  these  investigations  afford  a  basis  for  the 
explanation  of  the  failure  of  many  operations  conducted  on  the  lines 
of  the  accepted  anatomical  descriptions;  such  failures  have  been 
regarded  as  merely  the  natural  percentage  of  unsuccessful  treatment; 
whereas,  they  have  probably  been  due  to  variations  in  the  parts  clearly 
within  the  limits  of  normality.  This  will  be  demonstrated  in  the 
following   pages  by  many  illustrations. 

Anatomical  Variations. — Xo  man  who  spends  any  considerable 
portion  of  his  time  in  the  study  of  anatomy — that  is,  in  actual  dis- 
sections— can  fail  to  note  how  great  is  the  number  of  anatomical 
variations  which  he  meets.  So  common  are  these  that  it  cannot  be  said 
with  exactness  what  are  typical  and  what  are  atypical  conditions. 
In  other  words,  anatomy  as  a  study  is  not  to  be  classed  among  the 
exact  sciences.  It  is  not  meant  by  this  that  there  is  not  such  a  basis 
of  anatomical  science  that  general  rules  cannot  l)e  laid  down,  but 
the  more  closely  the  subject  is  studied  the  more  variations  as  to  details 


IS  INTRODUCTORY 

are  recorded.  From  the  mandible  of  an  animal,  a  femur,  or  even  a 
tarsal  bone,  the  nature  of  the  associated  bones,  their  sizes,  positions, 
and  forms  can  be  satisfactorily  deduced.  Admitting  this,  however, 
there  are  still  as  many  variations  in  the  internal  anatomy  as  there 
are  differences  in  the  external  appearances.  Especially  is  this  true 
of  the  anatomy  of  the  human  head,  as  it  is  modified  by  climate,  race, 
age,  disease,  occupation,  and  many  other  conditions. 

Climate. — Climate  and  environment  have  a  great  influence  in  modi- 
fying the  development  of  the  bones  of  the  head,  as  is  demonstrated  in 
the  differing  formations  of  the  skulls  of  the  great  races  of  the  world; 
and  more  markedly  in  branches  of  the  same  race  living  under  diverse 
climatic  and  social  conditions. 

Age. — The  changes  produced  by  age  are  very  marked.  The  skull 
consists  of  bones  of  both  cartilaginous  and  membranous  origin.  In 
the  fetus  and  infant  these  bones  are  soft  and  yielding;  they  receive 
deposits  of  certain  salts  of  calcium,  becoming  harder  and  harder  as 
age  advances  until  the  degeneration  of  senility  sets  in.  In  the  jaws, 
constant  changes  are  caused  by  the  development,  eruption,  and  loss 
of  teeth  and  the  consequent  alterations  of  the  alveolar  process. 

Disease. — Disease  causes  profound  changes  in  the  bony  structures 
as  well  as  in  the  other  tissues  of  the  body  (see  Fig.  45).  In  the  pres- 
ence of  some  disorders  of  the  nutritive  system — such  for  example,  as 
rickets,  either  the  bones  may  fail  to  become  infiltrated  with  a  sufficient 
quantity  of  lime  salts,  which  would  have  the  effect  of  leaving  them  soft 
and  yielding;  or,  on  the  other  hand,  an  undue  proportion  of  calcareous 
material  may  be  incorporated  into  the  bones,  with  the  opposite  effect 
of  making  them  hard  and  unyielding,  thus  modifying  the  physiological 
functions  with  which  they  are  concerned. 

Occupation,  Diet,  etc. — Occupation  will  modify  the  shape  and 
character  of  the  face  and  head,  especially  in  youth.  Those  persons 
who  are  studious,  and  pass  an  indoor  life,  are  likely  to  have  a  more 
delicate  development  of  the  face,  with  a  larger  brain-case  than  those 
who  are  brought  up  to  a  laborious  outdoor  life.  The  comminution  of 
coarser  foods  will  develop  the  muscles  of  mastication  and  their  bony 
attachments.      Numerous   other   facts    might    be    cited    to   show    the 


DIAGSOSTIC  IMPORTAXCK  19 

influences  of  personal  habit  upon  the  course  of  anat(^mical  develop- 
ment. 

Asymmetry. — There  are  also  variations  in  the  same  individual  in 
the  shape,  size,  and  markings  of  the  two  sides  of  the  face.  In  the 
bilateral  bones  such  as  the  frontal,  sphenoid,  vomer,  ethmoid,  and 
mandible,  one  side  is  usualh'  found  to  differ  fnjm  the  other.  In  the 
homonymous  bones,  as  the  maxilla?,  the  malar,  the  lachrymal,  the 
turbinate,  and  the  palate  bones,  the  same  variations  are  observed. 
This  being  the  case,  it  will  be  readily  understood  that  the  internal 
openings  and  spaces,  viz.,  the  mouth,  the  nasal  chambers,  the  orbits, 
the  maxillary-,  frontal,  and  sphenoidal  sinuses,  the  ethmoidal  and  other 
cells,  will  differ  accordini;ly. 

Diagnostic  Importance. — It  is  clear  that  variations  of  the  nature 
referred  to  must  have  a  direct  bearing  on  the  diagnosis  of  morbid  con- 
ditions for  which  there  is  no  evident  explanation,  and  even  more  so 
on  the  performance  of  operations  for  their  relief.  A  knowledge  of 
these  variations  will  point  the  way  to  an  understanding  of  many 
otherwise  obscure  and  doubtful  lesions.  It  will  also  show  why,  for 
example,  following  stereotyped  ideas,  the  surgeon  seeking  to  open 
into  the  antrum  will  occasionally  enter  the  nasal  cavity  instead.  It 
would  seem  that  to  the  surgeon,  and  more  especially  to  the  dentist, 
such  information  is  a  necessity. 

The  main  object  of  this  volume  is  to  present  a  digest  of  these 
revealed  facts  relating  to  the  internal  anatomy  of  the  face — facts  which 
have  an  important  bearing  on  all  surgical  operations  in\olving  this 
region,  and  especially  on  the  work  of  the  dentist  and  the  rhinologist. 
With  this  in  view,  the  aim  will  be  to  call  attention  to  misconceptions 
of  the  actual  conditions;  to  correct  errors  which,  having  found  cur- 
rency, have  been  commonly  accepted  and  more  especially  to  enforce 
the  idea  that  a  sla\ish  following  of  typical  descriptions  is  likely  to  lead 
to  disaster. 


CHAPTER  II. 
GENERAL   CONSIDERATIONS. 

Anatomical  Structures. — The  anatomical  bony  structures  of  the 
facial  region  include  the  framework,  superficially,  of  the  external  face 
and,  more  deeply,  the  walls  of  the  various  cavities  and  air  spaces  of 
the  internal  face.  As  with  other  bones,  they  consist  of  a  cortical  outer 
wall  inclosing  cancellated  tissue,  the  latter  being  extremely  fine  and 
delicate  in  many  cases,  in  some  instances  becoming  so  attenuated  as 
to  be  almost  lost.  The  exterior  cortical  parts  are  covered  with  a  true 
periosteum,  while  the  interior  surfaces,  those  looking  toward  the  inter- 
nal cavities,  as  the  mouth,  nasal  cavity,  the  frontal,  maxillary,  and 
sphenoidal  sinuses,  and  the  ethmoidal  cells,  are  covered  by  a  muco- 
periosteum.  From  these  characteristics,  the  former  are  known  as 
non-mucous,  and  the  latter  as  mucous  or  mucoid  surfaces.  It  is 
important  to  consider  the  difference  in  these  surfaces  in  the  treatment 
of  some  of  the  diseases  of  the  bones. 

The  dense  exterior  or  non-mucous  surface  is  roughened  at  various 
points  by  the  actions  of  the  attached  muscles.  The  exterior  cortical 
portion  varies  in  thickness  according  to  the  amount  of  work  to  which 
it  is  subjected  or  the  protection  it  has  to  afford.  The  greatest  thick- 
ness is  found  in  the  mandible,  the  active  bone  of  mastication,  which 
occupies  a  position  in  the  face  where  it  is  peculiarly  exposed  to  the 
effects  of  external  forces,  such  as  blows,  etc. 

The  inner  or  mucous  surfaces,  while  dense  and  compact,  are  thinner, 
smoother,  and  more  delicate.  They  are  marked  by  depressions  for 
the  lodgment  of  the  mucous  glands,  by  grooves  for  the  lodgment  of 
the  nerves  and  vessels,  and  also  by  elevations  due  to  the  attachment 
of  the  muscles. 

Cancellated  Structure. — The  cancellated  tissue  found  between  the 
plates  of  cortical  Ijone  varies  in  thickness  and  compactness  according 


DEVEWPMEXT  OF  THE  FACE  21 

to  the  (IcMisit)',  the  i)()siti()n,  and  the  functions  of  tlu'  bone.  '1  he 
arrangement  of  the  trabecuUe  is  an  interlacing  network.  T(;  give 
bulk  to  the  bone  where  required,  and  to  diffuse  shock,  constitute  the 
functions  of  the  cancellated  tissue.  Through  it  pass  the  nerves  and 
vessels  to  supply  local  structures  and,  by  means  of  bon\-  canals  or 
tubes,  the  more  distant  parts.  The  bones  of  the  head  contain  man\' 
canals  and  foramina  for  this  last-named  i^urjDose,  thus  differing  mate- 
rially from  the  other  bones  of  the  body.  This  is  a  fact  of  surgical 
importance.  For  when  these  bones  have  become  altered  either  by  the 
breaking  down  of  the  tissue  or  by  abnormal  growths  encroaching  uj^on 
the  foramina  or  canals,  the  functions  of  the  nerves  and  vessels  are 
interfered  with,  thus  affecting  not  only  adjacent  tissues,  but  parts  of 
the  face  and  body  remote  from  the  seat  of  the  lesion,  causing  abnor- 
malities in  the  area  of  distribution,  as  atrophy,  neuralgia,  etc. 

DEVELOPMENT    OF    THE    FACE. 

The  bones  of  the  brain  case  are  in  an  advanced  stage  of  develop- 
ment before  the  facial  bones  commence  to  be  built.  To  such  an  extent 
is  this  so  that  the  dermoid  structures  are  nearly  in  contact  with  all 
of  that  portion  of  the  head  below  and  anterior  to  the  notochord. 
At  this  time  there  is  no  opening  into  the  alimentary  canal. 

The  facial  bones  arise  from  the  under  surface  of  the  brain  case,  from 
certain  processes  that  push  outward  and  downward,  leaving  a  layer 
of  dermoid  tissue  on  their  inner  as  wxll  as  their  outer  surfaces.  This 
dermoid  tissue  becomes  the  mucous  or  epidermal  lining  of  the  mouth, 
the  nasal  cavities,  and  all  internal  surfaces  of  the  face. 

It  is  also  from  this  dermoid  tissue  that  the  teeth  and  alveolar  i)r{)- 
cesses  take  their  origin,  and  not  from  the  developing  buds  or  processes 
that  form  the  remainder  of  the  bones  of  the  face;  so  that  when  the 
teeth  are  lost  and  there  is  no  function  for  the  alveolar  ]:)rocess  to  per- 
form, it  is  also  lost.  It  is  for  this  reason,  also,  that  when  the  dermoid 
tissues  are  attacked  by  systemic  diseases  such  as  syphilis,  scarlet  fever, 
etc.,  the  teeth  and  alveolar  processes  are  involved  simultaneously 
with  the  skin,  as  are  also  the  bones  of  the  face,  which  were  covered 


22  GENERAL  CONSIDERATIONS 

originally  with  dermoid  tissue.  It  is  quite  possible  that  pyorrhea 
alveolaris  may  also  be  a  manifestation  of  a  dermoid  disease. 

When  the  dermoid  appendages  are  entirely  lacking  at  birth,  and 
do  not  develop  later  on,  the  alveolar  process  will  also  be  lacking. 

The  processes  in  front  which  pass  down  and  forward  are  called  the 
frontonasal;  those  on  the  side,  the  maxillary  and  mandibular;  those 
situated  deeply  within  the  face  are  known  as  the  spheno-ethmoid  pro- 
longations. The  general  tendency  of  these  buds,  forming  the  upper 
and  lower  jaws  is  to  send  processes  toward  the  median  line  w'hich  form 
a  union  with  their  fellows  of  the  opposite  side.  The  bonds  of  these 
unions  vary  accordingly  to  circumstances  depending  upon  their  posi- 
tion, function  and  the  age  of  the  individual. 


CHAPTER    IT  I. 

thp:  mandible  or  lower  jaw. 

Thk  niaiuliblc  dcxelops  Ironi  the  first  pair  of  the  \iscc-ral  or 
branchial  folds  called  the  mandibular  plates,  which  in  early  embryonic 
life  advance  from  the  sides  of  the  base  of  the  cranium  and  meet  al  the 
median  line,  forming  the  symphysis  menti. 

The  mandible  is  symmetrical  in  its  general  shape,  although  one 
side  may  and  usually  does  differ  from  the  other.     It  presents  for  study 


r-v 


c  D 

Fig.  1. — Four  mandibles  ranging  from  birth  to  eighteen  months:    .4,  at  birth;    B,  at  three  months; 

C,  at  six  months;    D,  at  eighteen  months. 

a  body  which  is  horizontal  in  direction,  with  two  rami  extending 
upward  to  the  articulation  in  the  anterior  portion  of  the  mandibular 
fossa  of  the  temporal  bones.  The  angle  (gonion)  formed  by  the  union 
of  the  lower  border  of  the  jaw  and  the  posterior  border  of  the  ramus, 
varies  considerably-  at  different  periods  of  life.  Eigs.  i,  2,  3  and  4  are 
views  of  the  external  cortical  surfaces  of  the  normal  lower  jaw  at 
various  ages,  showing  progressive  changes  in  the  angle  between  the 
rami  and  the  body  of  the  bone  as  life  progresses.  At  birth  {A,  Fig.  i) 
the  angle  is  very  obtuse,  but  as  the  teeth  develop  and  erupt,  it  becomes 


24 


THE  MAXDIBLE  OR  LOWER  JAW 


less  and  less  obtuse  until  about  the  time  the  last  of  the  permanent 
teeth  are  erupted  it  is  almost  a  right  angle,  as  shown  in  Fig.  2. 


Fig.  2. — Side  view  of  a  typical  mandible  at  maturity. 

As  the  muscles  grow  and  increase  in  strength,  that  portion  of  bone 
to  which  they  are  attached  also  increases  in  size,  giving  the  ramus  a 
square  appearance,  especially  in  strong  muscular  persons  (see  Fig.  8). 

After  full  maturity,  as  time  passes,  the  muscular  action  becomes 
less  and  less,  and  the  tuberosities,  etc.,  throughout  the  body  become 


Fig.  3. — Mandible  of  aged  person,  showing  a  great  change  from  that  of  adult  life. 

smaller.  The  same  condition  takes  place  at  the  angle  of  the  jaw,  and 
it  becomes  more  obtuse  as  age  advances.  When  the  jaws  can  be  kept 
apart  with  good  teeth  and  normal,  complete  mastication,  there  is  not 
so  much  change  in  the  angles. 


THE  MAXDIRLE  OR  LOWER  JAW 


l^o 


As  the  tc'C'lh  l)t'(()nu'  abraded,  or  when  they  are  extracted,  the 
alveolar  process  is  resorbed,  the  horizontal  i)lanes  of  the  jaws 
api)roach  each  other  more  closeK',  and  the  an^le  ai^ain  becomes 
obtuse   (see  Fig'.  3). 

The  teeth  and  their  alveolar  i)rocesses  are  placed  on  the  ui)i)er 
portion  of  the  l)()d>-  of  the  bone.  The  third  molar  is  partially  posterior 
to  the  anterior  margin  of  the  ramus,  and  a  line  can  l)e  drawn  between 
the  first  and  second  premolars  to  the  mental  foramen. 


Fig.  4. — Mandible  of  an  aged  person  showing  the  mental  foramina  in  the  top  of  the  body  of  the  jaw. 


The  incisor  teeth  should  have  neither  lingual  nor  lal)ial  inclina- 
tion. Fig.  2  shows  a  fairly  typical  mandible:  as  is  also  shown  in  the 
skull  marked  Fig.  77. 

The  mental  process  gives  prominence  to  the  chin  and  lower  part 
of  the  face.  It  belongs  to  man  only,  and  is  always  associated  with 
the  genial  tubercles.  In  the  monkey  there  is  a  depression  instead  of 
the   tubercles.    The   space   between    the   halves   of   the   body   of    the 


20  THE  MANDIBLE  OR  LOWER  JAW 

mandible  in  the  region  of  the  premolar  teeth  is  much  wider  in  man  than 
in  the  other  mammalia,  thus  giving  more  freedom  for  the  action  of  the 
tongue.  The  mental  process,  the  genial  tubercles,  and  the  freedom 
of  the  tongue  are  severally  and  collectively  concerned  in  the  produc- 
tion of  articulate  speech.  The  writer  also  considered  that  the  presence 
of  a  well-developed  mental  process  contributes  to  a  greater  command 
of  articulate  speech  than  can  be  attained  by  individuals  in  whom  it 
is  small  or  underdeveloped;  and  as  it  extends  outward  beyond  the 
line  of  the  teeth,  it — the  mental  process — gives  the  origin  for  the 
muscles  that  control  the  action  of  the  lower  lip,  and  when  properly 
developed  holds  the  latter  in  position  to  conform  with  the  upper  lip, 
thus  perfecting  the  labial  sounds. 

In  considering  the  manner  in  which  deaf  people  can  communicate 
orally  by  observing  the  action  of  the  lips,  and  the  fact  that  the  deaf 
and  blind  can  read  what  is  being  said,  merely  by  gently  placing  the 
fingers  upon  the  lips,  one  is  inclined  to  the  opinion  that  the  lips  are  an 
important  factor  in  the  communication  of  thought  as  well  as  in  the 
production  of  articulate  speech. 

The  orbicularis  oris  muscle  and  its  associates  must  have  great  free- 
dom and  power  of  action  in  order  to  produce  the  numberless  varieties 
of  motion  necessary  to  this  end.  The  facial  nerve  thus  becomes  one 
of  the  nerves  of  speech,  as  it  not  only  controls  the  lips,  but  also  the 
cheeks  and  some  of  the  muscles  of  the  soft  palate. 

In  order  that  these  oral  muscles  shall  have  a  free  and  balanced 
action,  the  lower  portion  of  the  orbicularis  and  its  associated  inferior 
muscles  must  be  carried  forward  to  a  line  equal  to  that  of  the  upper 
portion,  thus  as  before  mentioned,  the  mental  process  also  becomes 
an  important  factor  in  articulate  speech. 

Mandibles  of  Different  Races. — In  comparing  mandibles  of  different 
races  and  also  of  the  same  race  great  variations  in  general  characteristic 
shape  and  size  are  found.  The  following  figures  illustrate  a  few  of 
these  variations: 

Fig.  5  is  a  side  view  of  an  Indian  mandible  found  in  one  of  the 
buttes  in  western  Kansas.  It  is  a  very  powerful  jaw,  the  angle  is  almost 
acute,  1 06  degrees,  the  distance  from  the  condyloid  process,  which  acts 


MANDIBLES  Of  DIFFERENT  RACES 


27 


as  the  fulcrum,  to  the  coronoid  i)rocx^ss,  the  place  of  attachment  of  the 
temporal  muscle,  is  50  nun.,  which  i^ives  i^reat  jiower  to  the  mandible. 


50  MM 


Fig.  5. — A'powerful  mandible  of  an  Indian  found  in  buttes  of  western  Kansas.      (Loaned  by 

Dr.  Ketcham.) 


Fig.  6. — A  mandible  of  a  South  African  negro,  a  member  of  the  Fan  tribe. 


Fig.  6  is  from  a  mandible  of  a  South  African  negro  a  member  of  the 
Fan  tribe  (see  Fig.  78).  The  body  is  fairly  typical,  except  that  the 
angle   is   nearly   a   right   angle.     The   characteristic   features   of   this 


28 


THE  MAXDIBLE  OR  LOWER  JAW 


mandible  are  caused  by  the  position  of   the  teeth  and  their  alveolar 
processes,  which  are  set  forward  on  the  body  of  the  jaw.      It  will  be 


Fig.  7. — A  mandible  from  a  skull,  showing  prognathous  jaws.      (See  Fig.  79.) 

noticed  that  the  third  molar  is  in  advance  of  the  ramus  about  the 
width  of  a  molar,  and  that  a  line  drawn  downw^ard  between  the  pre- 
molar teeth  would  pass  across  the  body  of  the  jaw  a  full  width  of  a 
molar   tooth   in   advance   of   the   mental   foramen.     The   canine   and 


Fig.  8. — A  manclible  of  a  heavy  skull.      (See  Fig.  80.) 


incisor  teeth  are  placed  in  front  of  the  jaw  proper,  with  considerable 
labial  inclination  of  the  incisors.    The  mental  process  is  not  so  promi- 


MAXDIBLES  OF  DIFFERENT  RACES 


29 


nent  as  in  Fig.  2,  due  in  part  lo  the  carrying  f(jr\varcl  (jt  the  teetli 
and  alveolar  process. 

Fig.  7  is  made  from  a  skull  (see  Fig.  79)  showing  prognathous  jaws. 
In  Fig.  6  the  prognathism  is  evidently  caused  by  the  malposition  of 
the  teeth  and  their  alveolar  processes  upon  the  body  of  the  bone. 
In  Fig.  7  the  principal  cause  of  prognathism  is  in  the  relation  of  the 
ramus  to  the  body,  which  carries  the  body  of  the  jaw  so  far  forward 
that  the  mental  process  is  much  more  prominent  than  in  Fig.  6  and 
the  anterior  teeth  have  lingual  inclination. 

Fig.  8  is  made  from  the  mandible  of  a  very  heavy  skull  with  massive 
teeth    in    excellent    alignment    (see    Fig.    80)    and    when    articulated 


Fig.  9. — A  mandible  of  a  peculiar  skull.     (See  Figs.  363,  364  and  365.) 


with  its  skull  there  is  fairly  good  occlusion.  The  marked  feature  of 
this  mandible  is  the  relation  of  the  ramus  to  the  body  of  the  bone; 
its  external  angle  is  nearly  a  right  angle,  being  103°  on  the  right  side 
and  100°  on  the  left. 

Fig.  9  is  made  from  a  mandible  of  a  ])eculiar  skull  (see  Figs.  93,  363. 
364  and  365).  It  is  a  great  contrast  to  the  mandible  shown  in  Fig. 
8.  The  angle  of  the  ramus  with  the  body  of  the.  bone  is  139°.  Age 
should  be  taken  into  consideration  in  this  comparison,  as  the  angle 
usually  increases  as  age  advances. 

Fig.  10  is  made  from  the  mandible  of  a  skull  ha\  ing  a  \ery  flat  face 
(see  Fig.  82).  There  is  a  slight  anterior  occlusion.  The  angle  of  the 
jaw  is  obtuse — viz.,  133  degrees. 


30 


THE  MANDIBLE  OR  LOWER  JAW 


Fig.  II  is  made  from  the  mandible  of  a  Chinese  skull  (see  Fig.  8i). 
The  rami  are  rather  square  and  unite  with  the  body  of  the  bone  at  an 


Fig.  10. — A  mandible  from  a  skull  of  a  flat-faced  person.      (See  Fig.  82.) 

angle  of  io8°,  which  makes  the  mandible  short.     On  the  left  side  of 
the  mandible  there  is  an  impacted  lower  third  molar. 


Fig.  11. — A  mandible  of  a  skull  of  a  Chinese.     (See  Fig.  81.) 

The  following  diagrams,  each  reduced  one-half,  give  the  measure- 
ments and  angles  of  the  mandibles  in  Figs.  2,  6,  7,  8,  9,  10  and  11: 


MANDiniJ'S  OF  nil- F EKES T   RACES 


'M 


124*  ANGLE  75MM 

Fio.  12.— Mandible,  Fig.  2. 


M  ENTAL 
FORAMEN 


136'  77  MM 

Fig.  14. — Mandible,  Fig.  7. 


I39«  66  MM 

Fig.  16.— Mandible,  Fig.  9. 


118'  71  MM 

Fig.  13. — Mandible,  Fig.  6. 


MENTAL 
FORAMEN 


,03«  89  MM 

Fig.  15.— Mandible,  Fig.  8. 


MENTAL 
FORAMEN 


135°  73  MM 

Fig.  17.— Mandible,  Fig.  10. 


I'U;.  18.— Mandible,  Fig.  11. 

The  following   diagrams   illustrate    the  triangles  of   mandibles    in 
skulls  of  various  ages  from  eight  months  to  old  age: 


ISO*        42  n  M 
Fig.  19. — Age  eight  months. 


^lT  48    MM 

Fig.  20. — Age  fifteen  months 


32 


THE  MANDIBLE  OR  LOWER  JAW 


Fig.  21. — Age  eighteen  months. 


51)     MM 

Fig.  23. — Age  four  years. 


120'  65    MM 

Fig.  25. — Age  seven  to  eight  years. 


so  MM 

Fig.  22. — Age  two  years. 


IIS"  55   "^M 

Fig.  24. — Age  five  years. 


116"  62    MM 

Fig.  26. — Age  eight  to  nine  years. 


MS"  70MM 

Fig.  27. — Age  thirteen  years. 


106°  7t>     n  M 

Fig.  28.— Age  eighteen  years. 


77     r-iM 

Fig.  29.— Adult.  Fig.  .^0.— Old  age. 

Fi(;s.   19  to  30. — Diagrams  of  mandible,  reduced  one-half. 


THE  BODY  OF  THE  J  AW 


33 


The  Body  of  the  Jaw. — The  body  of  the-  jaw  in  Iransxcrsc  section, 
shows  a  r-sliai)C'(l  cortical  or  dense  l)()n\-  strnctnrc,  tlic  amis  of  the  U 
terminating  in  the  pkUes  of  the  alveoku-  process — outer  and  inner — 
which  are  composed  of  a  mocHhed  cortical  bone  with  no  dehnite  line 
of  demarkation  between  them  and  the  body  of  the  bone  proper;  the 


Fig.  M. — Anterior  lateral  view  of  upper  and  lower  jaws,  with  the  external  cortical  portion  of 
bone  covering  the  roots  of  the  teeth  removed,  exposing  the  cancellated  tissue,  the  roots,  and  the 
cribriform  tube.      (Mandibular  canal.) 

function   of   the   body,    however,    is   quite   different    from    that   of   the 

alveolar  process. 

The  bone  projXT  is  covered  with  a  true  periosteum,   the  alveolar 

process  with   mucoperiosteum.   the  latter  being  thick  and  dense  and 

containing   many    mucous   glands.      It    is   commonh-    known    as   gum 
3 


34 


THE  MANDIBLE  OR  LOWER  JAW 


tissue.  The  space  between  the  arms  of  the  U  is  filled  with  fine  trabe- 
culae  forming  the  cancellated  structure.  The  roots  of  the  teeth  are 
imbedded  within  this  cancellated  structure,  each  root  being  sur- 
rounded by  thin,  compact  bony  tissue.  Lamina  dura,Mvhich  approaches 
the  cortical  bone  in  density,  but  is  cribriform  (sieve-like)  in  character 
(see  Figs.  31,  32  and  34). 

Fig.  34  is  an  upper  view  of  the  mandible  with  the  teeth  removed, 
showing  single  sockets  for  the  ten  anterior  teeth  and  double  sockets 
for  the  six  molars.     The  shapes  of  the  sockets  as  shown  correspond 


Fig.  32. — Mandiljle  wilh  the  cortical  portion  of  bone  removed  from  the  body. 

with  the  transverse  section  of  the  various  teeth  at  the  level  of  the 
margins.     The  septa  between  the  sockets  are  cribriform  in  character. 

Cribriform  Tube. — Through  the  cancellated  tissue  passes  the  man- 
dibular canal,  which  is,  however,  more  accurately  described  by  the  term, 
"cribriform  tube  of  the  mandible."  The  function  of  this  tube  is  to 
afford  a  protective  passage  for  the  mandibular  nerve  and  the  blood- 
vessels. 

The  cribriform  tube  passes  downward  and  forward  from  the  man- 

'  A.  Hopewcll-Smith,  Dental  Cosmos,  August,  1913,  p.  769. 


CRIBRIFORM  TUBE 


35 


dibular  furanien,  at  first  along  the  inner  cortieal  portion,  then,  after 
it  leaves  the  ramus,  gradually  crossing  over  through  the  cancellated 
tissue  toward  the  outer  cortical  portion  and  downward  toward  the 
border  of  the  I  -shaped  space.  As  it  ai)proaches  the  mental  foramen, 
its  course  is  near  the  outer  cortical  portion  and  along  the  lower  border 
of  the  cancellated  tissue,  passing  beneath  the  foramen  to  its  termina- 
tion near  the  roots  of  the  incisor  teeth.  This  tube  can  be  removed  from 
a  normal  jaw  or  isolated  as  shown  in  Fig.  33,  taken  from  a  specimen 
in   which   the  cortical   and   cancellated   tissues   have  been   cut   away, 


Fig.  33. — Cribriform  tube  (mandibular  canal)  of  the  lower  jaw  isolated. 


exposing  the  cribriform  tube.  Figs.  31,  32  and  T,2t  show  that  the  crib- 
riform tube  is  an  independent  structure,  not  merely  a  canal  through 
the  bone.  In  Fig.  31  it  will  be  noticed  that  a  portion  of  the  outer  wall 
of  the  tube  has  been  removed,  while  in  Fig.  32  the  wall  is  left  intact, 
showing  its  tubular  form.  The  outer  wall  of  the  tube  in  the  region  of 
the  second  and  third  molars  is  extremely  well  shown  in  Fig.  31. 

As  the  tube  passes  along  the  jaw  its  cribriform  character  becomes 
more  and  more  marked  until,  beneath  the  first  molar  tooth,  it  becomes 
so  opened,   probably  by  a  sort  of  stretching  process  coincident  with 


36  THE  MANDIBLE  OR  LOWER  JAW 

the  growth  of  the  bone,  that  the  tube-Uke  formation  is  almost  lost,  as 
is  well  shown  in  Fig.  31.  Further  forward  it  again  resumes  its  original 
character.  This  main  cribriform  tube  gives  off  lesser  branch  tubes 
which  afford  passage  for  the  nerves  and  vessels  to  the  substance  of  the 
bone;  also,  in  more  or  less  curved  course  to  the  roots  of  each  tooth. 
The  branch  tube  for  the  accommodation  of  the  nerves  and  vessels 


Fig.  34. — View  from  above  of  mandible  from  which  all  the  teeth  have  been  removed,  showing  the 
cribriform  character  of  the  septa  of  the  sockets  of  the  teeth. 

to  the  mental  foramen,  is  usually  given  off  slightly  anterior  to  the 
foramen,  passing  backward  from  the  main  tube  to  the  foramen.  This 
is  almost  invariably  the  rule — namely,  that  the  tube  to  the  mental 
foramen  is  in  the  form  of  a  return  or  recurrent  canal,  mental  canal, 
though  occasionally  it  passes  from  the  main  tube  as  it  approaches 
the  foramen.  The  recurrent  tube  is  well  shown  in  Figs.  31  and  32. 
In  the  former,  the  anterior  wall  of  the  mental  foramen  has  been  cut 


METHOD  OF  CROW  Til  37 

a\va\',  and  in  llu-  latlcr.  a  narrow  piece  of  i)a])(  r  has  lieen  ])asse(l  llir(ni;<h 
llie  foramen  inlo  the  recurrent  tul)e,  showin.n  its  (Hrection. 

The  Dental  Branches. — The  small  lateral  tubes  which  serve  as 
nerve  and  vessel  conduits  to  the  roots  of  the  teeth  posterior  to  the 
mental  foramen  arc  p:ivcn  off  from  the  main  tube  and  pass  ui)\vard 
and  forward  in  a  more  or  less  curved  direction,  the  degree  of  cur\a- 
ture  varying  according  to  the  position  of  the  teeth.  Those  going  to 
the  third  molar  are  nearly  vertical  in  direction.  In  those  going  to 
the  second  molar  the  forward  direction  is  greater;  in  those  to  the  first 
molar  this  forward  direction  is  increased  still  more,  while  those  to  the 
second  ])remolar  have  the  longest  curve  of  all.  Sometimes  the  tube 
l)assing  to  the  second  premolar,  instead  of  beginning  at  the  main 
tube,  is  found  as  an  offshoot  of  that  going  to  the  anterior  root  of  the 
first  molar.  The  small  tubes  going  to  the  first  premolar  and  the  canine 
are  branches  of  the  recurrent  tube  of  the  mental  foramen,  and  are 
ciu'ved  slightly  backw^ard  as  they  pass  upward  to  the  roots.  In  the 
unusual  cases,  where  the  branch  from  the  mental  foramen  is  not  recur- 
rent, but  given  off  as  the  main  tube  approaches  the  foramen,  the  latter 
branches  for  these  two  teeth  pass  directly  from  the  main  tube,  and 
with  a  slight  forward  curvature.  The  tubes  for  the  supply  of  the  inci- 
sors are  also  branches  of  the  main  tube,  and  curve  slightly  forward  as 
they  pass  upward  to  the  roots. 

Method  of  Growth. — The  cortical  U-shaped  portion  of  the  bone  is 
the  framework  of  the  jaw;  its  supporting  structure.  It  grows  by  an 
interstitial  process,  each  half  having  three  fixed  points  between  which 
the  growth  occurs — viz.,  the  ramus,  the  mental  foramen,  and  the  sym- 
physis menti.  There  is  no  doubt  that  the  distance  between  these 
points  increases,  though  the  growth  between  the  symphysis  and  the 
foramen  does  not  occur  at  the  same  time  as  that  between  the  foramen 
and  the  ramus.  The  periods  of  grow^th  in  these  regions  seem  to  corre- 
spond with  the  time  of  development  and  eruption  of  the  teeth  of  the 
localities  concerned.  Thus,  the  increase  between  the  mental  foramen 
and  the  symphysis  menti  occurs  during  the  time  the  incisor,  canine, 
and  premolar  teeth  are  developing.  After  these  teeth  are  erupted, 
there  is  little  further  increase  in  the  length  of  this  ]X)rtion  of  the  jaw. 


38  THE  MAXDIBLE  OR  LOWER  JAW 

From  the  mental  foramen  to  the  ramus  the  increase  is  inconsiderable 
until  the  time  draws  near  for  the  eruption  of  the  second  and  third 
molars,  the  greatest  growth  occurring  during  the  development  of  these 
teeth,  and  generally  ceasing  after  the  eruption  of  the  last  named. 

The  contents  of  the  U-shaped  portion  grow  forward  as  the  cortical 
structure  increases  in  length,  the  teeth  immediately  posterior  to  the 
mental  foramen — which  are  first  developed  in  this  region — being  pushed 
forward  successively  by  each  developing  and  erupting  tooth.  It  is 
this  forward  movement  which  gives  the  curvature  to  the  various  small 
tubes  to  the  roots  of  the  teeth,  etc.,  and  accounts  for  the  stretching 
of  the  main  tube  until  its  distinctive  character  is  nearly  lost  under 
the  first  molar.  It  also  affords  a  rational  explanation  of  the  recurrent 
feature  of  the  tube  to  the  mental  foramen;  the  end  of  this  tube  being 
attached  to  the  wall  of  the  foramen,  when  in  the  process  of  growth 
the  mass  of  cancellated  tissue  is  pUvShed  forward,  the  tube  itself  is  carried 
along  with  it,  forming  a  loop. 

The  reason  why  the  small  tubes  going  to  the  first  premolar  and 
the  canine  curve  backward  is,  that  their  points  of  origin  have  been 
carried  forward  wdth  the  return  tube  from  which  they  spring.  The 
small  tubes  going  to  the  incisors  curve  slightly  forward,  as  they  arise 
from  the  continuation  of  the  main  tube  near  the  point  where  it  cur\'es 
backward  to  the  foramen. 

Surgical  Significance. — This  anatomical  arrangement  has  an  impor- 
tant surgical  significance  in  certain  phases  of  the  operation  of  resecting 
the  mandibular  nerve,  for  if  the  general  teaching  of  anatomy  be  fol- 
lowed the  surgeon  is  liable  to  be  misled.  If  the  operator  cuts  down  to 
the  mental  foramen,  then  seizes  the  mental  nerve  and  uses  it  as  a  guide 
while  cutting  the  bone  away  with  the  surgical  bur  from  the  posterior 
wall  of  the  foramen,  he  will  find  that  the  nerve  cannot  be  followed 
as  a  rule,  as  the  nerve  and  the  canal  do  not  pass  backw^ard.  But  if 
the  anterior  wall  be  cut  away,  the  nerve  can  be  followed  down  to  the 
mandibular  nerve,  which  may  then  be  uncovered  to  any  distance 
deemed  necessary. 

Pathological  Significance. — The  pathological  significance  of  this 
bending  backward  of  the  nerve  and  its  bony  covering  is  that  if  any 


METHOD  OF  GROWTH  39 

injur>'  be  received  in  this  region,  (^r  if  an>  inflammatory  condition 
be  produced,  cither  traumatically  or  by  infection  from  diseased  teeth, 
the  nerve  is  liable  to  become  inii)inged  upon  or  compressed,  thus 
causing  pain  or  inflammation  of  the  nerve  itself.  The  writer  has 
found  neuromata  more  common  in  this  region  than  at  any  other  portion 
of  the  mandibular  nerve,  probably  mainly  due  to  the  anatomical 
condition  under  consideration. 

Records  of  Development. — Thus  it  will  be  seen  that  the  anatomical 
structures,  the  relation  of  the  various  teeth  considered  with  regard 
to  the  order  of  their  development,  and  more  especially  the  direction 
which  the  lateral  branches  of  the  main  cribriform  tube  take  to  form 


Fig.  35. — View  of  mandible  (left  side),  with  the  cortical  portion  of  bone  removed  together  with 
the  cancellated  tissue,  exposing  the  nerves  and  vessels  within  the  cribriform  tubes  as  they  pass  to 
the  roots  of  the  teeth. 

their  connection  w4th  the  roots  of  the  several  teeth,  supply  us  with 
permanent  records  of  the  methods  of  growth  of  the  mandible  during 
the  period  between  childhood  and  adult  life. 

In  the  boiled  and  cleaned  specimen,  naturally  all  the  contents  of 
the  tubes — the  soft  tissues — have  disappeared;  but  the  illustrations, 
Figs.  31  and  32,  show  clearly  that  the  main  tube  and  the  smaller 
ones  passing  to  the  various  teeth,  and  the  finer  tubes  going  to  the  inter- 
spaces and  general  cancellated  tissue,  have  the  same  general  direction 
and  curvature  as  those  going  to  the  roots  in  their  immediate  vicinity. 

Fig-  35  shows  a  specimen  from  which  the  soft  tissues  have  not  been 
removed.     It  shows  the  smaller  tubes  passing  to  the  roots  of  the  teeth. 


40  THE  MAX  BIBLE  OR  LOWER  JAW 

with  their  contents,  proving  that  these  tubes  do  act  as  conduits  for  the 
nerves  and  bloodvessels. 

Fig.  36  is  from  a  specimen  which  was  prepared  b^^  grinding  away 
the  labial  and  lingual  surfaces  of  the  bone  and  teeth  until  the  pulp 
chambers  and  apical  foramina  were  exposed  on  both  sides  of  the  teeth, 
leaving  the  tissues  extending  out  of  the  foramina  and  through  a  por- 
tion of  the  bony  cribriform  tube  below.  In  one  tooth,  at  A,  the  lateral 
wall  has  been  broken  away,  leaving  the  tissues  uncovered  by  hard 
structures  on  the  three  sides.  It  will  be  seen  that  the  nerve  has  been 
pushed  slightly  away  from  the  wall.  In  this  dissection  and  in  many 
others  it  will  be  observed  that  the  tissues  passing  into  the  teeth  give 


Fig.  36. — Ground  section  of  the  six  anterior  teeth  and  two  left  premolars. 

off  small  branches  from  the  nerves  and  vessels  just  below  the  apical 
foramen.  So  clear  does  this  appear  that  the  writer  is  of  the  opinion 
that  the  lower  portion  of  the  alveolodental  periosteum  is  supplied  from 
the  same  branches  of  the  nerves  and  vessels  which  supply  the  pulp. 

Pathological  Significance.— -The  pathological  significance  of  this 
condition  is  found  in  the  reciprocal  relation  of  pulp  hyperemia  and 
congestion  with  the  same  conditions  affecting  the  apical  portion  of  the 
peridental  membrane  so  frequently  observed  in  clinical  practice. 

Fig.  37  is  a  vertical  transverse  section  through  the  jaws  and  tongue 
at  the  location  of  the  first  molars,  affording  a  good  idea  of  the  cortical 
portion  of  the  bone  heretofore  referred  to,  of  its  relation  with  the  roots 
of  the  teeth,  and  of  the  position  of  the  cribriform  tube  with  the  nerve 


METHOD  OF  CROW'TII 


for  which  il  scr\c's  as  a  conduit.     (For  further  (k'scrii)tion  oi  tliis  ilkis- 
tration,  sec  Fig.  196,  i)age  220.) 

Fig.  38  is  a  view  of  the  anterior  portion  of  the  lower  jaw  shown  in 
^^^8-  37-     Tl"^<-'  roots  of  the  second  premolar,  it  will  be  seen,  are  nearly 


Crystalline  lens 


Unciform  process 
Middle  concha 
Middle  meatus 
Maxillary  sinus 
Inferior  meatus 

Inferior  nasal 
concha 


Vestibule  of  the 
mouth 
First  molar 


Posterior  root  of 
first  molar 


Mandibular 
nerve 


Fig.  37. — Anterior  view  of  vertical  transverse  bilateral  section  of  the  head,  showing  the  relations 
of  the  jaws  and  the  U-shaped  cortical  bone  of  the  mandible. 

in  a  line  transversely  with  the  anterior  roots  of  the  first  molar,  a  con- 
dition which  is  not  at  all  uncommon.  As  the  premolar  roots  are  long 
and  comparatively  slender,  extending  below  the  roots  of  the  molar, 


42 


THE  MANDIBLE  OR  LOWER  JAW 


often  nearly  to  the  mandibular  nerve,  while  the  bone  at  this  point  is 
usually  ver^^  compact,  the  difficulty  occasionally  met  with,  in  extracting 
these  teeth  without  breaking  them,  is  readily  accounted  for. 

Surgical  Pathology. — The  relation  of  these  roots  to  the  cancellated 
tissue  of  the  jaw  has  a  pathological  significance.  If  their  pulps  become 
diseased  and  infected,  the  infectious  matter  may  pass  out  through  the 
comparatively  open  tissue  and  burrow  in  various  directions,  setting 
up  an  osteomyelitis  and  affecting  the  other  teeth,  eventually  causing 
an  abscess,  the  discharge  of  which  may  pass  either  through  the  mental 
foramen  or  through  the  alveolar  wall  into  the  mouth,  or  even  through 
the  main  portion  of  the  U-shaped  cortical  bone  into  the  neck.     The 


Anterior  root  of  first 

molar 
Root  of  second  premolar 


Mandibular  nerve 
U-shaped  cortical  bone 


Fig.  38. — A  posterior  view  of  an  anterior  transverse  section  of  the  mandible  made  through  the 
anterior  root  of  the  first  molar,  showing  the  U-shaped  cortical  bone. 


necrotic  process  thus  extended  may  include  in  its  destructive  area 
the  apical  regions  of  several  adjacent  teeth,  causing  devitalization  of 
their  pulps.  It  is  the  habit  of  some  practitioners  to  inject  hydrogen 
peroxide  through  the  diseased  teeth  into  abscesses  of  this  character 
even  before  an  external  opening  has  been  formed.  The  decomposition 
of  the  hydrogen  peroxide  in  contact  with  the  pus,  generates  gas  with 
great  force,  if  the  gas  has  not  a  perfectly  free  outlet,  it  will  burrow 
through  the  tissue  in  various  directions  of  the  least  resistance  and 
carry  infection  to  any  part  of  the  mandible.  The  writer  has  seen  cases 
in  which  the  use  of  this  drug,  continued  after  extraction  of  the  teeth 
has  resulted  in  the  loss  of  a  large  portion  of  the  jaw  (see  Fig.  39). 


METHOD  OF  GROWTH 


43 


Fig.  39  is  from  a  i^hutograph  of  three  secjuestra  produced  b>-  injecting 
hydrogen  peroxide  into  a  diseased  mandible,  the  bone  in  each  of  these 
cases  regenerated. 

Fig.  40  represents  the  left  side  of  a  lower  jaw  cut  lengthwise  nearly 
through  its  centre,  exposing  the  cancellated  tissue,  the  sockets  of  the 
teeth,  and  the  cribriform  tube  or  mandibular  canal,  with  its  branches 
to  the  alveoli.  As  the  tissue  is  very  frail,  a  considerable  quantity  of 
the  trabeculse  was  lost  in  the  cutting.  The  outer  section  shows  the 
direction  of  the  recurrent  tube  for  the  accommodation  of  the  mental 
nerve  and  vessels. 

Figs.  41  and  42  represent  two  sides  of  a  metal  cast  showing  the  can- 
cellated structure  within  the  U-shaped  portion  of  the  bone.    It  was  made 


~,,^^ 


Fig.  39. — Sequestra  from  a  mandible  producerl  by  the  use  of  hydrogen  peroxide. 


in  the  following  manner,  from  a  perfect  and  thoroughly  cleaned  jaw  with 
all  the  teeth  extracted.  After  covering  the  openings  of  the  sockets 
of  the  teeth  with  paper,  the  end  of  a  slender  tube  about  eighteen  inches 
long  was  inserted  in  the  mandibular  foramen.  The  bone  and  tube  were 
then  invested  in  plaster  of  Paris  mixed  with  a  little  asbestos.  After 
the  investment  was  thoroughly  set  and  dried,  it  was  heated  to  about 
212°  F.,  and  a  metal  of  low  fusil)ility  was  poured  into  the  tube.  This 
metal  passed  into  the  cribriform  tube  and  along  its  course,  finding 
its  way  out  through  the  many  openings  into  the  cancellated  tissue  and 
into  the  sockets  of  the  removed  teeth.  After  the  plaster  investment 
was  removed,  the  body  of  the  bone  and  the  lower  portion  of  the  ramus 
were   j^laced    in   a   10   i)er  cent,   solution  of   hydrochloric   acid,   which 


44 


THE  MANDIBLE  OR  LOWER  JAW 


dissolved  the  lime  salts  away,  except  where  particles  of  the  cancellated 
tissue  are  seen  as  white  spots  appearing  through  the  metal.  A  trans- 
verse section  of  this  preparation  would  show  fine  threads  of  bony 
tissue  through  the  body  of  metal. 

Fig.  41  shows  the  inner  surface,  in  which  the  cast  of  the  canal  or 
tube  may  be  seen  also  the  space  occupied  by  the  red  marrow  of  the 


Fig.  40. — Longitudinal  divisifjn  of  a  mandible,  exposing  the  cancellated  tissues  in  the  body  of  the 

iaw  and  between  the  sockets  of  the  teeth. 


bone,  the  nerves,  bloodvessels,  and  their  membranes.  In  Fig.  42, 
which  pictures  the  outer  surface,  the  dense  sj^ot  near  the  border  beneath 
the  second  i)renKjlar  indicates  where  the  nerves  and  vessels  passed  out 
of  the  mental  foramen. 

Fig.  43  is  from  a  horizontal  section  of  the  upper  and  lower  jaws,  a 
little  beyond  the  free  margins  of  the  alveolar  processes.     It  shows  the 


METHOD  OF  GROWTH 


45 


Fig.  41 


Fig.  42 
Figs.  41  and  42.— Two  views  of  the  sides  of  a  metal  cast  of  the  open  spaces  in  the  body  of  the 

mandible. 


46 


THE  MAXDIBLE  OR  LOWER  JAW 


shape  and  position  of  the  various  roots  on  that  plane,  and  their  rela- 
tion to  the  process  and  to  one  another.  The  conditions  here  shown 
are  so  common  as  to  warrant  their  classification  as  the  normal  type. 


First       Second 
incisor     incisor     Canine 


First  premolar 


Second  premolar 


Third 
molar 


Second  molar 
First  molar 


Second  premolar 


First  premolar 


Fig.  43. — Horizontal  sections  of  the  maxilla  and  mandible  cut  a  little  beyond  the  free  margin  of 
the  alveolar  process,  showing  the  forms  and  positions  of  the  roots  of  the  various  teeth. 

Particular  attention  is  drawn  to  the  slight  distance  between  the  roots 
and  the  plates  of  the  alveolar  process.  It  would  be  manifestly  impos- 
sible in  the  operation  of  extraction,  to  force  the  beaks  of  forceps  between 


METHOD  OF  GROWTH 


47 


the  roots  and  the  aUeolar  i)r<jcess  in  such  cases  wilhoul  breaking  the 
latter  on  one  or  both  sides.  The  not  infrequent  splitting  off  of  a  section 
of  the  alveolar  process  in  extraction  is  thus  readily  accounted  for.  The 
lines  in  the  cut  represent  the  strongest  axes  in  the  teeth,  those  along 
which  the  greatest  force  is  e.xerted  in  extracting  operations,  and  which 
are  usually  at  the  same  time  the  lines  of  least  resistance  of  the  sur- 
rounding tissues. 


Mandibular 

nerve 

Roots  of 

third  molar 


Roots  of 
second  molar 

A  root  of. 
first  molar 

Root  of  second 
premolar 

Root  of  first 
premolar 


Root  of  canine  Root  of  left  second  incisor 

Fig.  44. — Horizontal  section  of  the  mandible  cut  in  the  region  of  the  points  of  the  roots  of  the  teeth. 

The  roots  of  the  teeth  extend  to  various  depths  in  the  lower  jaw.  as 
is  seen  in  Fig.  44,  which  represents  a  section  cut  horizontally,  from  the 
same  subject  as  Fig.  43,  though  nearer  to  the  ends  of  the  roots.  The 
ends  of  the  roots  of  the  second  and  third  molars  are  plainly  seen,  also 
the  tip  of  one  of  the  roots  of  the  first  molar,  and  the  roots  of  the  first 
and  second  premolars.  A  little  of  the  second  incisors  will  be  noticed, 
but  the  roots  of  the  first  incisors  do  not  extend  down  so  far.  The  can- 
cellated portion,  with  the  soft  tissue  filling  the  spaces,  is  well  shown 


48  THE  MANDIBLE  OR  LOWER  JAW 

in  the  posterior  portion  of  this  picture.     The  nerve  is  seen  passing  into 
its  tube. 

If  all  mandibles  with  their  teeth  were  like  those  just  described, 
surgery-  of  the  lower  jaw  would  be  comparatively  simple.  In  fact, 
there  would  be  little  to  do  except  in  cases  of  traumatism;  but  unfor- 
tunately this  is  not  the  case,  as  will  be  demonstrated. 

INFLAMMATORY    CHANGES. 

Inflammation  within  the  lower  jaw  caused  by  diseased  teeth,  or  by 
constitutional  disturbances,  may  completely  change  the  character  of 
both  the  cancellated  and  cortical  portions,  by  stimulating  the  bone- 
building  cells  of  these  tissues  to  undue  activity.  Under  such  circum- 
stances, the  cancellated  tissue  may  be  filled  up  or  converted  into  a 
substance  so  nearly  resembling  the  cortical  bone  that  the  line  of  demar- 
cation is  obliterated;  while  the  cortical  portion  may  be  solidified — 
made  more  dense,  ivory-like — and  thickened,  presenting  conditions 
which  very  much  complicate  the  situation  and  make  the  performance 
of  operations  difficult,  and  sometimes  impracticable  by  the  usual 
methods. 

Fig.  45  is  taken  from  a  section  made  transversely  through  the  lower 
jaw  at  the  mental  foramen  of  each  side.  On  the  left  side  the  cortical 
U-shaped  portion  and  the  cancellated  tissues  are  about  normal  and  in 
condition  similar  to  those  in  Figs.  31  and  32,  while  on  the  right  side  the 
cortical  portion  has  thickened  and  become  dense,  and  the  cancellated 
tissue  has  become  filled  with  a  deposit  of  secondary  bone.  The  only 
apparent  reason  for  this  difference  is  that  all  the  teeth  on  the  left  side 
were  in  good  condition,  while  on  the  right  side  the  first  molar  had  been 
much  diseased,  causing  the  inflammation  of  that  side  of  the  jaw; 
vascular  changes  induced  activity  of  the  functions  of  the  osteoblasts, 
which  caused  the  deposit  of  secondary  bone. 

Inflamed  conditions  in  the  jaws  of  children,  occasioned  either  by 
abscessed  teeth  or  by  constitutional  distur])ances,  will  cause  the  deposit 
of  secondary  bone  within  the  cancellated  tissue,  binding  it  to  the 
U-shaped  cortical  portion.     In  such  cases,  when  the  time  for  the  erup- 


NECROSIS  AXD  REGEXERATIO.X 


49 


tion  of  the  molars  arrixes,  especially'  of  the  second  and  third,  it  is 
impossible  for  the  cancellated  tissue  and  the  erupting  teeth  to  glide 
forward  as  shown  in  Fig.  32.  Many  cases  of  imi)action  of  the  third 
molar  are  doubtless  due  to  the  existence  of  such  conditions. 

Surgical  Pathology. — The  normal  and  pathological  anatomy  of  the 
two  sides  of  the  jaw  shown  in  Fig.  45  would  recjuire  different  modes 
of  surgical  procedure.  The  teeth  on  the  right  side,  being  placed  in  an 
unyielding  bone,  would  fracture  in  an  attempted  extraction,  and  the 
roots  would  remain  in  the  jaw.     The  cutting  of  the  bone  down  to  the 


/^s^ 


m,iu 


^W^ 


Fig.  45. — Transverse  division  of  a  mandible  at  the  mental  foramina.  The  left  side  is  in  an  almost 
normal  condition,  while  on  the  right  side  the  cortical  bone  has  thickened  and  become  dense,  and  the 
cancellated  tissue  has  become  filled  with  secondarj-  bone. 

mandibular  canal  and  nerve  on  the  left  side  in  a  case  of  this  character 
would  also  be  quite  a  dilTerent  operation  from  a  similar  operation  on 
the  right  side.  The  first  would  be  done  with  ease,  the  other  with  difih- 
culty,  and  when  the  cutting  was  done  it  would  be  difficult  to  find  and 
remo\e  the  nerve.  Correction  of  irregularities  of  the  teeth  in  the 
consolidated  area  would  be  almost  impossible. 


NECROSIS    AND   REGENERATION. 

The  formation  of  new  bone  to  repair  fractures  throughout  the  human 

body  is  known  tcj  and  ol)served  by  all  surgeons,  but  the  reproduction 
4 


50  THE  MANDIBLE  OR  LOWER  JAW 

of  large  portions  of  the  mandible  has  not  received   the  attention  it 
deserves. 

Before  going  into  the  details  of  this  reproduction  in  the  mandible 
it  might  be  well  to  speak  of  the  general  growth  of  bone,  about  which 
there  seems  to  be  a  difference  of  opinion. 

Many  of  the  text-books  on  general  anatomy  and  even  some  of  the 
modern  works  on  surgery,  teach  that  the  growth  of  bone  depends  to 
a  great  extent  on  the  presence  of  the  periosteum.  Keen's  Surgery,^ 
states,  "In  the  long  bones  the  vitality  of  the  bone  depends  upon  its 
relation  to  the  periosteum  and  marrow.  These  two  structures  should 
be  respected.  In  young  persons  the  periosteum  will  regenerate  new 
bone,  and  this  property  often  may  be  used  to  the  great  advantage  of 
the  patient." 

"The  periosteum  is  the  most  active  osteogenic  agent,  but  the  medulla 
is  also  very  active — Osteophytes  may  develop  during  the  healing  of  a 
fracture.  They  are  most  apt  to  spring  from  points  of  tendinous  inser- 
tion or  from  misplaced  pieces  of  the  periosteal  tissue."- 

On  the  other  hand.  Dr.  Clarence  A.  McWilliams,  of  New  York,  on 
"The  Periosteum  in  Bone  Transmission,"  says,^  "The  theory  that 
contact  with  living  bone  is  necessary  for  the  subsequent  life  of  grafts 
must  be  given  up.  Living  bone-grafts  have  life  inherent  in  them- 
selves and  are  capable  of  permanent  growth  even  when  transplanted 
into  the  soft  parts — 48  per  cent,  of  my  bone  grafts  without  periosteum 
were  successful  whether  contact  with  living  bone  was  made  or  not — 
periosteum  transplanted  into  the  soft  parts  will  produce  new  bone  in  a 
certain  proportion  of  cases." 

Dr.  Alexis  Carrell  and  Montrose  T.  Burrows,  of  the  Rockefeller 
Institute,  New  York,  have  reported  in  their  article  "Cultivation  of 
Adult  Tissues  and  Organs  Outside  of  the  Body."^  "During  the  first 
hours  of  the  cultivation  of  fragments  of  bone  marrow  and  bone,  the 
anatomic  elements  began  to  wander  away  from  the  tissue.  After  three  or 

•  Keen's  Surgery,  vol.  v,  p.  732. 

^  Park's  Surgery,  third  edition,  p.  576. 

'Journal  of  the  American  Medical  Association,  January  31,  1914,  p.  351. 

'  Ibid.,  October  15,  1010,  p.  13X0. 


NECROSIS  AM)  REGEXERATIOX  51 

four  (la>s,  the  lit  lie  pieces  of  hoiie  hidden  in  the  marrow  heconie  \isii)le, 
because  ahiiosl  all  the  eells  had  in\  aded  the  i)lasniatic  niediuin.  Around 
the  tissue,  there  were  radiating  spindle  cells  and  nian\-  red  Mood  cor- 
puscles. Leukocytes  with  active  ameboid  motion  and  lari^e  cells  with 
granular  cytoi)lasm  and  long  pseudopcxlia  had  reached  the  remotest 
part  of  the  medium.  A  few  large  spindle  cells  were  seen  crawling  along 
the  edges  of  the  fragments  of  bone." 

Sir  William  Macewen  of  Glasgow,  has  reported  his  experiments  in 
his  most  \aluable  work'  that  the  growth  and  repair  of  bone  does  not 
depend  upon  the  periosteum.  One  of  his  concluding  remarks  is,  "W'liile 
not  underestimating  the  periosteum  as  a  limiting  and  protecting  mem- 
brane of  great  use  in  physiological  and  pathological  conditions,  there  is 
no  data  to  indicate  that  it  can  of  itself  secrete  or  reproduce  bone.  It 
has  no  osteogenic  function." 

The  process  of  normal  growth  of  the  mandible  in  length  is  quite 
different  from  that  o(  the  long  bones,  as  there  are  no  epiphyseal  ends 
with  the  growth-producing  intervening  cartilage.  As  before  stated, 
the  growth  of  the  mandible  depends  on  an  interstitial  process  which 
varies  in  different  portions  of  the  bone  at  different  periods  of  life. 
This  variation  is  to  accommodate  the  development,  growth  and  erup- 
tion of  the  teeth  into  their  normal  positions.  If  there  be  no  living 
bone  left  on  either  side  of  that  portion  lost  by  pathological  condi- 
tions or  traumatism,  there  wull  be  no  regeneration  of  new  bone,  as 
this  process  for  the  repair  of  fractures  and  to  furnish  new  bone  is 
procured  through  the  working  of  the  osteogenic  system  in  the  bone 
remaining. 

In  looking  up  literature  of  regeneration  of  the  mandible  the  writer 
tinds  very  little  as  compared  with  that  written  upon  the  regeneration 
of  other  bones.  The  most  modern  works  on  surgery  with  a  few  excep- 
tions scarcely  mention  it. 

The  following  is  taken  from  Park's  Surgery,  third  edition,  page  550, 
under  the  head  of  phosphorus  necrosis:  "In  aggravated  cases,  such 
as  are  rarely  if  ever  seen  today  since  legislation  has  been  brought  to 

'  The  Cirowth  of  Bone. 


52  THE  MAXDIBLE  OR  LOWER  JAW 

bear  upon  the  subject,  practically  complete  necrosis  of  the  lower  jaw, 
either  en  masse  or  in  portions,  was  far  from  unknown,  and  the  possi- 
bilities of  regeneration  of  the  bone  was  for  a  long  time  discredited, 
until  the  late  James  R.  Wood  of  New  York  exhibited  a  specimen, 
both  at  home  and  abroad,  which  proved  its  possibility.  Since  then  we 
have  learned  that  it  is  possible  for  bone  thus  to  regenerate,  the  cause 
of  the  disturbance  having  been  removed." 

One  of  the  most  interesting  papers  upon  the  subject  of  regenera- 
tion of  the  mandible  was  written  by  Dr.  Percy,  of  Paris,  in  1791, 
reporting  five  cases  of  regeneration  of  half  or  more  of  the  lower  jaw 
which  had  been  destroyed  by  caries.^ 


Fig.  46. — Sequestra  from  tubercular  necrosis. 

Cases  of  necrotic  conditions  of  the  mandible  are  of  frequent  occur- 
rence; some  are  of  slight  extent  only,  caused  by  infected  teeth,  which 
by  proper  treatment  recovered  in  a  short  time.  There  are  many  others, 
however,  where  the  whole  mandible  is  more  or  less  involved,  the  gums 
and  the  soft  tissues  along  the  lower  portion  of  the  bone  become  very 
much  swollen,  the  teeth  loosen,  and,  though  at  first  there  may  be  no 
sign  of  pus,  in  a  few  days  it  will  exude  from  around  the  necks  of  the 
teeth  and  may  also  begin  to  point  in  one  or  more  places.  Free  incisions 
should  be  made  both  in  the  mouth  and  along  the  under  surface  of  the 
bone,  it  sometimes  being  necessary  to  drill  through  the  cortical  portion 
of  the  bone  to  obtain  as  free  drainage  as  possible.  On  passing  a  probe, 
denuded  bone  will  be  found,  which  condition  may  extend  all  along  the 
outer  and  under  surfaces  of  the  bone  from  the  symphysis  menti  to  the 

'  Journal  de  Medecine  tie  Chirurgic  ct  de  Pliarniacie,  Paris,  1791. 


NECROSIS  AM)  RKGENERATIOX 


53 


ramus  and  upwartl  t(j\\ard  the  nuiiulibular  iKUch.  On  opening  ihc 
tissue  so  that  the  outer  surface  of  the  bone  may  be  examined,  the  bone 
will  be  found  lo  be  somewhat  darkened  in  color,  there  being  numerous 
small  soft  tiixjts  indicating  patches  of  caries,  and  in  many  cases  the 
periosteum  is  absent  having  been  lost  by  suppuration. 


Fig.  47. — X-ray  picture  of  hydrogen  peroxide  necrosis.     (A'-ray  by  Dr.  Pancoast.) 


Fig.  46  is  made  from  a  necrotic  sequestra  and  four  teeth,  which  had 
been  removed  from  a  tubercular  patient.  The  bone  around  the  roots 
of  the  teeth  was  so  fragile  that  it  crumbled  in  pieces,  leaving  only  a 
little  band  of  soft  connective  tissue  holding  the  teeth  together,  the 
condyloid  and  coronoid  processes  were  left  in  position.  On  removing 
the  sequestra  new  bone  could  be  felt  at  the  bottom  of  the  space  which 


54  THE  MAXDIBLE  OR  LOWER  JAW 

eventually  became  entirely  filled  with  osseous  tissue.  The  patient  was 
of  course  edentulous,  but  had  a  new  half  of  a  mandible  well  covered 
with  gum  tissue  and  in  good  union  with  the  other  half.  There  was 
no  ankvlosis. 


Fig.  48. — A'-ray  picture  of  phosf)horus  necrosis,  showing  new  bone  formation  on  the  lower  border 

of  mandible.     {X-ray  by  Dr.  Pancoast.) 

Fig.  47  is  taken  from  an  .x-ray  picture,  vshowing  not  only  the  spots  on 
the  surface  but  those  in  the  internal  structure  of  the  bone.  The  body  of 
the  jaw  appears  to  be  in  an  advanced  stage  of  necrosis,  pus  exuding 
through  the  tissue  into  the  mouth  at  several  points  and  through  two 
external  sinUvSes.    The  history  of  the  case  gave  a  diseased  premolar  tooth 


XKCROS/S  AM)   l<l'r.li.\ER.\ri()\  55 

which  had  Ix-cn  trt'aR'd  1)\-  Inch'o^fn  pcrcjxitk',  then  extracted,  but 
the  tisc  of  tlic  <hii,i;  was  continued  in  the  treatment  of  the  socket  and 
injecle<l   into   tlic   bone.     Sucli  cases  are  constantK'  (jccurrint;  from  the 


Fig.  49. — A'-ray  showing  necrotic  condition  of  nian(lii)lc.      (.Y-ray  by  Dr.  Pancoast.) 

use  of  hydroi^en  i)eroxidc  ujion  diseased  jaws.  This  treatment  should 
be  discontinued  at  once  and  the  parts  kept  thoroughly  cleansed  by 
saline  solutions. 


56  THE  MANDIBLE  OR  LOWER  JAW 

Fig.  48  is  made  from  an  .v-ray  picture  of  the  necrosed  mandible  of 
a  man  who  worked  in  a  match  factory.  It  shows  a  diseased  condition 
of  the  entire  mandible  due  to  phosphorus  necrosis,  but  at  the  same  time 
a  rim  of  new  bone  forming  along  its  base. 

The  following  interesting  case  disclosed  on  examination  complete 
pathological  separation  of  the  mandible  on  the  left  side  in  the  region 
of  the  mental  foramen.  The  bone  and  apparently  the  periosteum 
had  been  lost  in  the  region  of  the  second  premolar,  the  bone  around 
the  first  premolar  was  in  a  necrotic  condition  and  the  ends  of  the 
mandible  on  either  side  of  the  necrotic  area  were  quite  separated. 
Mastication  was  impossible  and  speech  very  much  interfered  with. 
The  mandibular  nerve  had  been  divided,  causing  complete  numbness 
of  all  that  part  supplied  by  it  anterior  to  the  lesion.  This  numbness 
continued  for  over  a  year  after  successful  treatment  and  regeneration 
of  the  bone. 

It  would  be  interesting  to  know  just  how  the  reestablishment  of 
sensation  occurs  in  such  cases.  It  is  a  simple  matter  to  understand  the 
regeneration  of  a  nerve  where  it  does  not  pass  through  a  long  bony 
canal  as  in  the  mandible.  When  the  body  of  the  mandible  or  any 
portion  of  it  involving  the  canal  has  been  lost  by  necrosis  it  is  a  ques- 
tion whether  regeneration  of  the  bone  is  accompanied  by  reformation 
of  the  canal  and  nerve,  there  seems  to  be  no  affirmative  evidence  of 
this  on  record.  In  the  opinion  of  the  author,  reestablishment  of  sen- 
sation in  parts  normally  supplied  by  the  mental  nerve  is  due  to  trans- 
ference of  this  function  to  branches  of  the  cervical  plexis,  and  other 
branches  of  the  fifth  nerve,  and  not  to  regeneration  of  the  mandibular 
nerve  in  the  body  of  the  bone. 

Figs.  49,  50,  51  and  52  are  made  from  jc-ray  pictures  of  a  patient 
of  Dr.  R.  Hamil  D.  Swing's.  The  patient,  a  boy,  aged  seven  years, 
had  a  badly  swollen  face  with  pus  discharging  in  the  mouth  and 
through  a  sinus  in  the  neck.  In  October,  19 12,  an  .r-ray  picture 
was  made  (see  Fig.  49)  which  shows  the  necrotic  condition  of  the 
body  of  the  mandible,  with  two  developing  teeth.  It  also  shows  a 
portion  of  new  bone  forming  apparently  from  the  old  bone.  The  new 
bone  has  a  process  extending  backward  in  the  direction  of  the  coudyle, 


NECROSIS  .  I M)  REGENERA  TION 


57 


although  a  sliorl  portion  of  tin-  old  1)oik'  was  complctul^'  clcnudi-d.  1 1 
was  thought  best  to  axoid  the  rcniox  al  of  llic  dead  bone  so  that  it 
might  act  as  a  splint  to  the  new   bone. 


Fig.  5U. — A'-ray  showing  regeneration  of  bone.      iA'-ra\  1)\   Dr.  Pancoast.) 


Fig.  50  is  an  .v-ra\'  i)irture  taken  \o\ember  29.  1913.  showing  two 
thin  i^ieces  of  lead  wire  passing  around  the  remains  of  the  original  bone 
which  is  much  reduced  in  thickness.  The  portion  between  the  rings 
of  wire  is  cjuite  denuded,  and  can  be  plainly  seen  within  the  mouth. 


58  THE  M  Ay  BIBLE  OR  LOWER  JAW 

Under  the  dead  bone  that  is  surrounded  by  the  wires,  the  new  bone 
may  be  seen  to  be  forming,  showing  the  new  angle  very  plainly.  The 
old  angfle  can  also  be  seen. 


Fig.  51. — X-ray  showing  regeneration  of  bone  of  right  half  of  mandible.     (A'-ray  by  Dr.  Pancoast.) 


Fig.  51  is  from  an  x-ray  picture  taken  June  6,  1914.  It  shows  a 
further  increase  in  the  size  of  the  new  bone  and  a  deterioration  of  the 
old  bone. 

X-ray  pictures  were  taken  from  time  to  time  to  watch  the  process  of 
regeneration.  In  February,  1915,  the  anterior  end  of  the  old  bone  near 
the  canine  tooth  became  loosened,  the  posterior  end  being  still  attached. 
On  May  18,  191 5,  Dr.  Swing  removed  the  necrosed  jaw  (see  Fig.  52).  Had 


FRACTURES  OF   THE  .\L\M)IBLE  59 

this  (lead  hone  been  removed  as  soon  as  dia^iKJsed,  the  anteri(;r  jKjrticjn 
of  the  mandible  would  have  moved  backward  and  Xo  the  side,  but  by 
keeping  the  old  bone  in  place,  in  tlie  nature  of  a  splint,  it  gave  time  for 
a  new  half  4iiandible  to  be  regenerated.  In  all  such  cases  the  j^atient 
must  be  carefully  watched  as  to  general  health,  the  mouth  must  be 
kept  as  clean  as  possible  to  a\oid  general  septic  troubles.  Had  there 
been  an\'  indication  of  dislurl)ance  it  would  ha\e  been  necessary  to 
remove  the  dead  bone,  fortunateh'  the  child  remained  healthy  through- 
out the  degeneration  of  the  old  bone,  and  practical  exi)erience  has 
demonstrated  that  when  a  patient  is  in  good  healthy  condition,  with 
no  constitutional  disease,  it  is  possible  to  await  developments  despite 
the  necrosed  condition  of  the  jaw. 


Fig.  52. — Sequestrum  from  diseased  mandible. 

Fig.  52  is  a  sequestrum  taken  from  diseased  mandible,  as  shown  in 
Figs.  49.  50  and  51. 

FRACTURES    OF    THE    MANDIBLE. 

Owing  to  the  exj)osed  position  of  the  mandible,  fractures  may  occur 
at  the  symphisis  at  the  mental  foramen,  at  the  angle,  at  the  neck  of 
the  condyloid  process  or  any  intermediate  portion  of  the  bone. 

Fractures  of  the  mandible  arc  similar  in  character  to  those  of  the 
other  bones,  though  compound  fractures  are  most  common;  the  dis- 
placement of  the  parts  is  caused  by  the  action  of  the  various  muscles 
attached  to  the  bone.  The  displacement  is  sometimes  ver>^  marked, 
especially  in  a  double  fracture. 


60  THE  MAXDIBLE  OR  LOWER  JAW 

Fractures  associated  with  the  mouth  are  very  apt  to  become  a 
source  of  infection,  not  only  to  the  surrounding  tissue  but  to  the 
general  s\stem. 

In  treatment,  teeth  and  any  fragments  of  bone  found  in  connection 
with  the  break  should  be  removed,  and  everything  possible  be  done 
to  avoid  sepsis.  Wiring  of  the  teeth  or  the  screwing  of  metal  plates 
across  the  fracture  should  be  avoided. 

Cases  of  simple  fracture  with  but  little  displacement,  can  be  treated 
by  the  use  of  Barton  bandage,  reinforced  when  necessary  by  crinolin 
and  plaster  of  Paris.  If  a  bandage  of  this  character  becomes  stretched, 
it  should  be  cut  in  four  places,  the  "slack"  taken  out  and  the  places 
reunited  by  adhesive  strips. 


Fig.  53. — An  interdental  splint  on  a  fractured  mandible. 

The  best  splints  arc  of  two  characters:  First,  a  swaged  metal 
interdental  splint  as  shown  in  Fig.  53;  second,  a  swaged  and  soldered 
metal  maxillomandibular  splint  as  shown  in  .x-ray  picture  (Fig.  54). 
When  splints  of  this  character  are  properly  made  and  cemented  into 
place  the  bandage  can  be  discarded. 

Fracture  of  the  neck  of  the  condyle  is  difficult  to  diagnose.  The 
principal  symptoms  are  pain  in  the  c(jndyloid  region  and  malocclusion 
of  the  teeth,  the  molar  teeth  of  the  broken  side  striking  together  before 
the  others.  X-ray  i)ictures  should  be  made  in  both  lateral  and  antero- 
posterior directions.     The  latter  pictures  should  show  the  head  of  the 


FRACTURES  OF   THE  M.WDIBLE 


01 


coikKIl'  carric'tl  inward  aiul  forward  as  scc-n  in  Figs.  55,  56,  57  and  5<S. 
In  these  fractures  the  continued  actions  of  the  temporalis,  the  masse- 
ter  and  pterygoideus  internus  pull  the  ramus  upward  and  backward 
inUil    the   broken    v\u\   of    the   ramus   strikes   the   eon(l\loid    fossa,    the 


Fig.  54. — .Y-ray  showinp;  a  niaxilloniandibiilar  splint  in  position.     (A'-ray  by  Dr.  Pancoast.) 


muscular  action  of  the  pterygoideus  extern  us  carries  the  head  of  the 
condyle  forward  and  inward,  and  it  unites  1)\"  ossitication  in  this 
position. 

The  best  operation,  so  far  suggested  for  treatment  soon  after  the 
accident,  is  to  get  all  teeth  in  normal  occlusion,  if  possible,  ar.d  hold 


62 


THE  MANDIBLE  OR  LOWER  JAW 


them  there  by  a  maxillomandibular  spHnt.  By  inaction,  the  muscles 
of  mastication  will  relax,  which  will  allow  the  head  of  the  condyle  to 
take  a  fairly  normal  position. 


f-x\  \ '  ^  i^^ 


4 


Fig.  55. — A  mandible,  showing  the  left  condyle  in  an  abnormal  position. 

If,  as  is  the  usual  w^ay,  the  head  of  the  condyle  is  allowed  to  unite 
in  the  position  show^n  in  the  illustrations,  the  best  treatment  is  to  have 
a  dentist  correct  the  occlusion  as  far  as  possible  by  mechanical  means. 


Fig.  56. — Showing  a  reunited  fracture  of  the  neck  of  the  condyle  in  an  abnormal  position. 

Fig.  55  is  taken  from  a  mandible  showing  the  right  condyle  in 
normal  position,  while  the  left  is  fairly  typical  of  a  fractured  neck  of 
the   condyle.     The   action  of   the   pterygoideus  externus  carried    the 


FKACTLRES  OF  THE  MAXDIBLE 


03 


Fig.  57. — Side  view  of  a  skull  showing  fractured  neck  of  the  condyle. 


Fig.  58.— Anterior  view  of  a  skull,  showing  the  po-^ition  of  the  condyle  process  after  the  fracture 

of  its  neck. 


64  THE  MANDIBLE  OR  LOWER  JAW 

head  of  the  condyle  forward  and  inward  in  which  position  the  osseus 
union  of  the  parts  occured. 

The  relations  between  the  head  of  the  condyle  and  the  mandibular 
foramen  would  more  than  likely  interfere  with  the  mandibular  nerve 
and  vessels.  This  illustration  also  shows  that  there  had  been  another 
fracture  extending  from  between  the  second  incisor  and  canine  teeth 
downward  through  the  body  of  the  bone. 

Fig.  56  is  from  a  similar  specimen,  showing  similar  condition  of  the 

head  of  the  condyle. 

Fig.  57  is  a  side  view  of  a  skull  showing  fracture  of  the  neck  of  the 
condyle,  the  head  of  the  condyle  is  bent  inward  and  forward  until 
it  nearly  forms  a  right  angle  with  the  ramus. 

Fig.  58  is  an  anterior  view  of  a  skull,  showing  the  mandible  (Fig. 
55)  in  position.  The  right  side  is  normal,  the  left  side  shows  the  con- 
dyle carried  forward  and  inward  until  it  rests  in  the  sphenomaxillary 
space.  X-ray  pictures  of  the  living  subjects  will  show  similar  condi- 
tions. 

NEURALGIA. 

Secondary  bone  deposit  in  the  cortical  and  cancellated  tissue  of 
the  face  is  an  important  factor  in  producing  facial  neuralgia,  as  branches 
of  the  trigeminal  nerve  pass  through  not  only  to  the  bone  itself,  but 
also  to  the  region  beyond  in  various  directions.  In  the  left  side  of  Fig. 
45  the  spaces  are  comparatively  open,  while  the  right  side  of  the  same 
jaw  is  nearly  solid;  nerves  passing  through  this  half  would  be  impinged 
upon,  and  neuralgia,  the  cause  of  which  would  be  difficult  to  determine, 
would  result.  In  neuralgia  from  this  cause,  the  obvious  treatment 
would  be  the  burring  away  of  the  greater  part  of  the  abnormally  solidi- 
fied bone,  using  the  surgical  engine,  a  much  better  agent  for  its  removal 
than  the  ordinary  mallet  and  chisel. 

SECONDARY    DEPOSITS. 

The  cancellated  portion  of  the  mandible  usually  increases  in  com- 
pactness as  persons  advance  in  years.  Along  with  the  progressive 
increase  in  density  of  the  tissues  due  to  advancing  years,  other  factors, 


SECO.X  I).  \RV  D  EPOS  I TS 


(m 


pathological  in  rharatlcr,  1)\-  which  the  teeth  become  diseased,  set  u\) 
an  inflammatory  condition  which  causes  secondary  deposits. 

Fig.  59  shows  several  sections  from  a  lower  jaw,  which  was  ncjt 
quite  normal,  there  being  evidence  of  past  inflammation  having  changed 
the  structure  of  the  bone.  Several  teeth  had  been  extracted  before 
death.  In  some  of  the  sections  only  one  canal  is  seen,  while  in  others 
several  appear,  necessitating  close  observation  t(j  decide  into  which 
the  main  ner\es  and  vessels  have  passed. 


F  G  H  I  J 

Fig.  59. — Sections  made  at  different  points  from  a  mandible  which  was  not  quite  normal  in  its  density. 


In  the  resection  or  removal  of  the  entire  nerve  from  the  bone,  a 
surgeon  not  anticipating  this  condition  might  easily  clean  out  a  portion 
of  a  canal  without  touching  the  main  nerve.  This  mistake  might  not 
occur  in  the  dry  bone,  but  in  the  living,  where  the  parts  are  vascular, 
the  error  could  easily  be  made.  In  section  D  (Fig.  59)  it  will  be  seen 
that  the  anterior  root  of  the  second  molar  penetrates  the  true  mandib- 
ular nerve  canal.  In  case  of  abscess  of  this  root,  the  discharge  would 
5 


66 


THE  MANDIBLE  OR  LOWER  JAW 


flow  into  the  nerve  canal,  thence  backward  or  forward  along  the  nerve, 
causing  great  pain  h\  compression. 

Fig.  60  represents  a  specimen  in  which  the  roots  of  the  third  molar 
passed  out  through  the  inner  wall  of  the  lower  jaw,  at  a  considerable 
distance  below  the  mylohyoid  ridge.  A  putrescent  pulp  in  this  tooth 
would  have  discharged  its  infective  matter  at  once  into  the  submaxillar^^ 
triangle.  The  writer  believes  that  there  are  many  serious  unrecognized 
cases  where  devitalized  teeth  of  this  character  cause  infection  of  the 


c- 


Fig.  60. — Part  of  a  mandible,  showing  the  roots  of  the  third  molar  tooth  passing  through  the 
inner  wall  into  the  submaxillary  fossa. 

tissues  of  the  neck,  and  even  of  the  thoracic  cavity.  Therefore,  if 
diseased  teeth  in  this  region  do  not  respond  to  treatment  at  once,  they 
should  be  extracted,  as  not  only  ill  health,  but  death  itself  may 
occur  from  their  presence.  The  writer  has  seen  large  triangular 
swellings  just  under  the  jaw,  which  indicated  that  there  was  a  focus 
of  disease  within  the  submaxillary  triangle,  a  symptom  of  an  enlarged 
submaxillary  gland.  Upon  examination  of  the  teeth  a  diseased  molar 
was  found,  and  after  this  tooth  was  removed  the  swelling  subsided. 


MASDIini.AR   TKI.WCLE 


07 


MANDIBULAR    TRIANGLE. 

A  marked  \ariation  of  the  lower  jaw  is  found  in  the  relative  dis- 
tances between  the  centres  of  the  two  condyles  and  betw^een  these  and 
the  first  incisors.  These  measurements  have  been  commonly  accepted 
as  describing  an  equilateral  triangle.  The  measurements  of  the  jaws 
which  have  j^assed  through  the  writer's  hands  do  not  bear  out  this 
hypothesis.  In  fact,  the  variations  are  as  great  as  in  any  other  feature 
of  the  face.  In  only  one  case  w^as  an  exact  equilateral  triangle  found. 
Some  approached  that  figure,  but  in  the  great  majority  the  sides  of 
the  triangle,  taking  the  distance  between  the  centres  of  the  two  con- 


FiG.  61 


Fig.  62 


Figs.  61  and  62. — Two  mandibles  showing  variations  in  distance  between  the  two  condyles  and 

from  the  condyles  to  the  incisor  teeth. 

dyles  as  the  base,  considerably  exceeded  the  length  of  the  base.  In 
rare  instances  the  base  exceeded  the  length  of  the  sides.  The  varia- 
tions here  noted  would  seem  to  indicate  that  while  the  equilateral 
triangle  may  be  assumed  as  a  general  basic  principle  in  the  architecture 
of  the  lower  jaw,  the  variations  are  the  anatomical  facts  with  which 
we  arc  practically  concerned  so  long  as  the  hypothetical  form  remains 
unproved. 

Figs.  6 1  and  62  are.  made  from  photographs  of  two  jaws  in  which 
rather  extreme  conditions  were  found.  In  Fig.  61  the  base  of  the 
triangle  is  nearly  one-third  shorter  than  either  of  the  sides.  In  Fig.  62 
the  base  exceeds  either  side.     Between  these  extremes  (and  probabh'  to 


C8 


THE  MAXDIBLE  OR  LOWER  JAW 


some  extent  beyond  them  on  either  side)  every  variation  in  the  rela- 
tion of  the  sides  to  the  base  of  the  triangle  may  be  found  in  normal  jaws. 
In  this  description  of  the  lower  jaw  or  mandible,  the  intention  has 
been  to  emphasize  the  necessity  for  the  surgeon  to  promptly  recognize 
departures  from  the  accepted  diagrammatic  form  of  the  normal  jaw, 
and  the  results  of  pathological  changes  in  its  structures.  The  attempt 
has  been  to  illustrate  this  necessity  by  typical  cases  which  should  serve 
to  enforce  principles,  rather  than  enter  into  details. 

THE    MANDIBULAR    ARTICULATION. 

The  mandibular  articulation  is  formed  by  the  condyloid  process 
.of  the  mandible  and  the  anterior  portion  of  the  mandibular  fossa  of 


F"iG.  63. — Lateral  section  showing  the  relation  between  the  condyle  and  the  acoustic  meatus. 


the  temporal  bone  with  the  articulating  disk  between.  The  petro- 
tympanic fissure  is  immediately  behind  the  condyle  with  the  articular 
tubercle  in  front. 

This  articulation  brings  the  mandible  into  close  relation  with  one 
of  the  most  important  bones  of  the  cranium — the  temporal.  This 
bone  forms  a  portion  of  the  base  of  the  brain  case,  it  contains  the 


THE  MAXDIHULAK  ARTICLLATION 


i\\) 


canal  through  which  the  carotid  artcr\'  passes  to  supply  the  greater 
part  of  the  brain  and  the  vyv,  in  the  j)osterior  portion  is  the  great 
groove  for  the  lateral  sinus,  the  nerve  of  facial  expression  passes  through 
a  tortuous  canal  in  the  bone,  and  the  organ  of  the  special  sense  of 
hearing  is  located  in  the  ])etrous  portion,  in  close  juxtaposition  to  the 
condyloid  process  of  the  mandible. 


Fig.  64. — \'ertical  section  showing  meatus,  acoustic  tube,  middle  ear,  etc. 

Fig.  63  is  made  from  a  specimen,  showing  the  relation  between  the 
condyloid  process  of  the  mandible  and  the  mandibular  fossa,  the  exter- 
nal acoustic  meatus  and  the  parotid  gland. 

Fig.  64  is  a  vertical  section  made  through  the  left  ear,  giving  a 
posterior  view  of  the  external  acoustic  meatus,  the  tympanic  membrane 
and  cavity,  the  auditor^•  tube,  and  a  section  of  the  condyle.  A  most 
important  point  is  the  relation  of  the  cond\  le  to  the  temporal  bone  and 


70  THE  MAXDIBLE  OR  LOWER  JAW 

its  surrounding  tissue;  the  attachment  of  the  pterygoideus  externus 
is  well  shown.  In  case  of  fracture  of  the  neck  of  the  condyle,  the  mus- 
cular fibers  would  pull  the  head  of  the  process  inward  and  forward  as 
described  under  the  fracture  of  the  neck  of  the  condyle. 

The  movements  permitted  by  the  mandibular  articulation  are 
more  varied  and  of  a  greater  number  than  those  of  any  joint  in  the 
body.  The  jaw  has  the  power  of  extension  and  retraction,  on  one  or 
both  sides,  it  can  be  depressed  and  elevated,  moved  from  side  to  side, 
and  combines  all  the  movements  intermediate  betw^een  these,  thus 
allowing  the  gliding  motion  necessary  to  mastication.  The  articular 
disk  (interarticular  fibrocartilage)  probably  -assists  in  these  varied 
movements  and  acts  as  a  multiplier  of  them. 

If  the  mechanism  of  the  articulation  of  the  mandible  be  carefully 
examined,  it  will  be  found  that  the  sphenomandibular,  temporo- 
mandibular, and  stylomandibular  ligaments  act  as  suspensories  to  the 
jaw  and  have  a  tendency  to  fix  the  angle  when  it  is  carried  slightly 
downward  and  forward,  as  when  the  mouth  is  partially  opened.  The 
muscular  fibers  of  the  pterygoideus  internus  and  the  external  portion 
of  the  masSeter  muscles  have  the  same  tendency.  The  condyloidjirp- 
cess  of  the  mandible  acts  as  the  fulcrum  or  pivotal  point  of  the  bone. 
The  point,  or  fulcrum,  mainly  through  the  action  of  the  pterygoideus 
externus,  moves  forward  with  its  cushion,  the  articular  disk.  While 
the  jaw  is  being  carried  forward  the  mouth  can  be  opened  slightly, 
still  retaining  the  fulcrum,  or  pivotal  point  at  the  end  of  the  condyle, 
but  as  the  mouth  is  opened  wider,  the  fulcrum  is  gradually  changed 
from  the  condyle  toward  the  more  central  portion  of  the  ramus  and 
then  toward  the  angle,  probably  eventually  becoming  the  fulcral 
point  through  the  partial  fixation  of  the  ligaments  and  muscles  before 
referred  to.  By  the  action  of  the  pterygoideus  externus,  the  condyle 
is  drawn  forward,  and  the  mouth  is  thrown  w4de  open,  with  the  con- 
dyle under  or  slightly  in  advance  of  the  artldulai^  tubercle,  as  shown 
in  radiograms  taken  when  the  mouth  is  wide  open.  It  is  thus  that 
the  pterygoideus  externus  becomes  an  opener  of  the  mouth.  The  reason 
for  the  change  of  fulcrum,  or  pivotal  point,  may  be  found  in  the  con- 
dition which  is  obtained  in  the  pharyngeal  region.     If  in  opening  the 


THE  }fA.\I)nULAR  ARTICr LATION 


71 


nioulli  \vi(k'  llu'  licad  ol  the  (oiuKk'  acted  within  the  niandibular  fossa 
as  the  only  pivotal  point,  the  lower  portion  oi  the  ramus  with  the  body 
of  the  bone,  the  hyoid  bone,  the  base  of  the  tongue,  and  other  asso- 
ciated tissues  would  be  carried  backward  until  the  soft  tissue  coming 
against  the  postpharyniieal  wall  w(nild  interfere  with  the  functitms  of 
that  region.  By  the  transfer  of  the  jjoint,  this  interference  is  avoided. 
In  man  the  mandibular  articulation  presents  the  combination  of 
an  arthrodial  and  a  gingl>mus  or  hinge  joint.  In  the  carnivora,  this 
joint  has  no  gliding  movement  as  the  condyle  is  a  half  cylinder  working 


Fig.  65. — Side  view  of  a.  skull  of  a  Hydrocherus  capybara. 


Fig.  66. — Under  view  of  a  skull  of 
a  Hydrocherus  capybara. 


in  a  deep  mandibular  fossa  of  corresponding  form,  which  onh-  allows 
an  up  and  down  or  hinge  movement.  In  some  of  the  herbivora  the 
condyles  of  the  mandible  are  only  slightly  convex  and  the  mandibular 
fossa  of  the  tenijioral  bones  are  but  slightly  concave.  This  arrange- 
ment allows  great  latitude  of  motion,  and  the  gingh  mo-arthrodial 
nattire  of  the  joint  is  somewhat  greater  than  it  is  in  man.' 

The    mandibular    articulation    of    the    rodents    is    quite    different. 


'  For  full  anatomical  description  of  this  joint  see  general  text-book  on  anatomy. 


72  THE  MANDIBLE  OR  LOWER  JAW 

Figs.  65,  66  and  67  are  three  views  of  the  Hydrocherus  capybara, 
the  largest  rodent  now  Hving. 

Fig.  65  shows  the  grinding  teeth  in  occlusion.  It  will  be  noticed 
that  the  lower  incisors  are  considerably  posterior  to  the  upper. 

Fig.  66.  It  will  be  noticed  that  the  mandibular  fossa  (groove)  is 
quite  long  anteroposteriorly,  which  allows  great  latitude  in  carrying 
the  lower  jaw  forward  and  permits  the  upper  and  lower  incisors  to  come 
into  contact  for  gnawing  purposes  while  the  posterior  teeth  do  not 
occlude. 

The  structure  of  these  teeth  consist  of  enamel  plates  somewhat 
like  those  of  the  elephant  though  the  cement  substance  only  binds  the 
centres  of  the  plates,  leaving  knife-like  edges  on  the  lingual  and  buccal 
surfaces,  and  partially  on  the  occluding  surface. 


Fig.  67. — Side  view  of  a  mandible  of  a  Hydrocherus  capybara. 

Fig.  67  gives  a  lateral  view  of  the  mandible  of  Fig.  65,  showing 
that  the  condyloid  process,  the  occluding  surfaces  of  the  grinding 
teeth  and  the  incisors  are  nearly  in  a  straight  line  and  that  the  angle  of 
the  jaw  extends  backward  beyond  the  vertical  line  of  the  condyles. 

If  the  mandibular  articulation  of  a  vertebrate  be  shown  to  one 
familiar  with  the  anatomy  and  occlusion  of  the  teeth  in  relation  to 
this  joint,  he  could  readily  classify  the  animal  and  give  the  character 
of  the  mandibular  articulation  also  of  the  maxillary  sinus  and  the 
alimentary   canal. 

At  birth  the  mandibular  articulation  of  the  vertebrates  is  very 
similar;  l)ut  as  life  advances  the  similarity  disappears,  conditions 
change  in  proportion  to  the  environment  and  character  of  the  food. 
In  man  the  mandibular  fossa  is  quite  fiat  at  birth,  and  there  is  but 


THE  M:\.\I)IBL  LM<  AKTICLLATIOX 


73 


little  change  until  the  child  begins  to  masticate,  it  then  deepens  rapidly 
until  about  i)ubert>-.  As  age  advances  the  articulation  again  changes 
and  the  mandibular  fossa  becomes  more  flattened  like  that  of  child- 
hood. 

Fig.  68  is  made  from  a  side  view  of  a  human  skull  al  the  tiiue  oi 
birth.  The  mandible  articulates  in  its  fossa,  the  conch  loid  process 
is  in  close  juxtaposition  to  the  acoustic  process.  The  fossa  is  flat  and 
shallow,  the  condyles  are  short  and  rounded.     Posterior  to  the  fossa, 


Fig.  68. — Side  view  of  skull  at  l)irth. 


is  the  acoustic  ring  upon  which  the  tympanic  membrane  is  suspended, 
and  also  upon  which  the  greater  portion  of  the  wall  of  the  external 
acoustic  meatus  is  built,  there  is  but  little  change  until  sometime 
after  birth,  it  will  be  noticed  how  slight  is  the  protection  o\er  the 
organ  of  hearing  and  the  articulation.  An  inflammatory  condition 
of  this  region  from  any  cause,  could  produce  various  kinds  of  mal- 
occlusion of  the  teeth  and  serious  acoustic  troubles. 

Fig.  69  is  made  from  the  under  surface  of  a  human  skull  at  birth. 
It  will  be  observed   that  the  lower  jaw  occludes  within   the  upper. 


74 


THE  MAXDIBLE  OR  LOWER  JAW 


The  condyloid  process  is  close  to  the  wall  of  the  external  acoustic 
meatus.  Part  of  the  tympanic  membrane  and  the  auditory  ossicles 
have  been  preserved,  but  there  is  no  bony  protection  to  these  delicate 
structures  at  this  period,  consequently  they  are  often  injured  at  the 
time  of  birth  by  the  use  of  forceps. 

Fig.  70  is  made  from  a  side  view  of  a  skull,  showing  a  slight  forward 
occlusion  of  the  mandibular  teeth.  It  will  be  noticed  that  the  man- 
dibular articulation  is  quite  like  that  of  the  carnivora,  the  fossa  being 


Fig.  69. — View  of  base  of  skull  at  birth. 


deep  and  narrow,  allowing  but  little  play  in  the  joint.  The  anterior 
wall  of  the  external  acoustic  meatus  is  defective,  its  resorption  may 
have  been  caused  by  the  pressure  of  the  condyle,  or  the  wall  may 
never  have  been  formed. 

There  are  many  cases  where  the  anterior  osseous  wall  of  the  acoustic 
meatus  is  lacking  and  where  the  condyle  presses  against  the  mem- 


THE  MAXDIIULAR  ARTICULATION  75 

branous  mealu>.  iluis  iiUe'rferin^  with  hearing.  Otologists  treating 
such  cases  often  request  the  i)alient  U)  open  the  nioulli  wide,  this 
usually  draws  the  condyle  forward,  giving  a  clear  \  iew  U)  the  tympanic 
nuMiibrane. 


Fig.  70. — Side  view  of  skull,  showing  forward  occlusion  of  mandibular  teeth. 

From  the  relation  shown  in  the  structure  of  the  mandibular  articula- 
tion, it  is  very  evident  that  in  changing  the  position  of  this  articulation, 
a  forward  placement  of  the  jaw  could  be  accomplished  with  less  risk 
than  a  backward  placement. 

These  pathological  points  should  be  taken  into  consideration  when 
applying  pressure  on  the  lower  jaw  for  correction  of  malocclusion. 


CHAPTER    IV. 
THE   MAXILLA. 

The  upper  jaw,  from  a  surgical  point  of  view,  includes  the  right 
and  left  maxilla,  part  of  the  ethmoid  and  sphenoid  bones  of  the  cra- 
nium, and  in  addition  all  the  other  facial  bones  except  the  mandible. 
The  surgical  operation  of  removing  the  right  or  left  maxilla  does  not 
usually  involve  the  removal  of  the  entire  bone,  for  the  frontal  process, 
the  floor  of  the  orbit,  and  the  zygomatic  surface  may  be  left.  In  its 
removal,  however,  the  inferior  concha,  portions  of  the  lacrimal,  the 
palatal,  the  zygoma,  and  the  ethmoid  bones  will  probably  be  removed 
with  it.  Especially  is  this  true  in  the  general  method  of  operating, 
but  if  the  resections  are  made  with  the  assistance  of  the  surgical  engine, 
the  greater  portion  of  the  associated  bones  may  be  left  undisturbed. 

Architectural  Features. — The  maxillae  are  situated  beneath  the  walls 
of  the  anterior  fossae  of  the  brain-case  and  rather  loosely  attached 
by  what  may  be  termed  buttresses  and  flying  buttresses.  In  the  centre, 
near  the  nasion,  the  frontal  processes  rest  firmly  against  a  buttress 
in  the  median  line,  the  maxillary  processes  of  the  frontal  bone. 
Below  is  a  flying  buttress,  the  nasal  septum,  especially  that  portion 
formed  by  the  vomer,  which  passes  upward  and  backward  from  the 
interarticulating  ridge  of  the  maxillae  and  palate  bones  to  the  buttress- 
like body  of  the  sphenoid  bone,  where  it  is  firmly  held  or  braced  in 
place  by  the  vaginal  processes.  Laterally  the  upper  jaw  is  supported 
through  the  zygomatic  bones  by  the  zygomatic  processes  of  the  frontal 
bone  and  the  flying  buttresses  of  the  zygomatic  arches  to  the  temporal 
bones  at  the  sides  of  the  skull;  posteriorly  by  the  pterygoid  process 
of  the  sphenoid,  with  a  portion  of  the  palate  bone  interposed. 

The  buttresses,  situated  and  distributed  as  they  are,  not  only  afford 
support  against  forces  acting  externally,  but  also  dissipate  and  diffuse 
shocks  which  would  otherwise  be  transmitted  to  the  cranium.  As  a 
consequence  of  its  construction,  but  little  force  in  a  forward  direction 


THE  ALVKOLAR   PROCESS  77 

is  necessary  to  delacli  the  ui)i)c'r  jaw  from  the  craniiini,  lli<>u;^li  it  will 
withstand  a  blow  of  i>reat  force  received  from  below  tlirouLili  the  lower 
jaw  or  from  in  front,  or  even  from  the  side. 

Pathological  Relations.— The  upper  jaw  i^ives  sup[)orL  t<j  one-half 
of  the  teeth  and  like  the  mandible  is  subject  to  defects  of  development 
and  to  \  arious  pathological  changes,  chief  among  which  may  be  men- 
tioned cleft  palate  congenital  or  accjuired,  necrosis,  caries,  sarcoma, 
odontoma,  odontocele,  impacted  and  supernumerary  teeth.  It  may 
also  be  afTected  by  alveolar  and  dento-alveolar  abscesses,  diseases  of 
the  mucous-lined  sinuses  and  air  spaces,  which  last  may  also  give  rise 
to  such  symptoms  as  imj^aired  respiration  and  the  discharge  of  ofTen- 
sive  matter.  Tumors  or  abscesses  of  the  maxillary  sinus  often  grow 
to  such  a  size  as  to  elevate  the  floor  of  the  orbit,  depress  the  roof  of  the 
mouth,  and  force  outward  the  walls  of  the  cavity,  distorting  the  con- 
tour of  the  face  in  the  region  of  the  canine  fossae.  Neuralgia  in  the 
teeth  may  be  symi^tomatic  of  disease  of  the  bones  of  the  jaw,  and 
neuralgia  in  many  regions  of  the  head  is  traceable  to  the  teeth. 

The  under  surface  of  the  upper  jaw  is  bounded  by  the  alveolar 
process  and  the  roof  of  the  mouth  or  the  palatal  processes,  both  of 
which  are  covered  by  periosteum  and  mucous  membrane  (mucoperi- 
osteum).  That  portion  of  the  mucous  membrane  over  the  alveolar 
process  is  thick  and  dense,  and  is  known  as  gum  tissue;  it  contains 
but  few'  mucous  glands,  while  the  portion  covering  the  roof  of  the 
mouth  is  not  so  dense,  and  is  well  supplied  with  racemose  mucous 
glands. 

The  Alveolar  Process. — The  alveolar  process  is  made  up  of  two 
plates,  an  external  and  an  internal,  consisting  of  dense,  compact,  cor- 
tical bone.  The  outer  plate  extends  upward  and  -merges,  without  a 
line  of  demarkation,  into  the  outer  surface  of  the  true  maxilla.  The 
inner  plate  extends  upward  and  inward  and  is  continuous  with  the 
palatal  process  of  the  palate  bone  and  maxilla  proper.  The  space 
between  the  plates  is  occupied  by  the  sockets  of  the  teeth,  the  alveoli, 
which  are  surrounded  by  a  \ery  thin  cribriform  plate  of  bone  (the 
lamina  duraO  by  cancellated  tissue,  nerves,  vessels,  etc.    The  alveolar 

1  A.  Hopewell-Smith,  Dental  Cosmos,  August,  1913. 


78  THE  MAXILL.E 

process  belongs  to  the  teeth  and  is  developed  with  them  for  the  pur- 
pose of  holding  them  in  position.  It  disappears  in  various  degrees 
after  the  teeth  are  lost,  sometimes  before,  more  especially  when  there 
is  pyorrhea  alveolaris,  and  also  as  an  indication  of  advancing  age. 
Should  the  alveolar  process  be  the  primary  seat  of  disease,  sound  teeth 
will  loosen  and  mav  fall  out.  The  outer  alveolar  plate  is  resorbed  after 
the  loss  of  the  teeth  to  a  greater  extent  than  the  inner  one,  which  is 
of  advantage  to  the  dentist  in  fitting  artificial  teeth  to  the  gums;  con- 
sequently, in  extracting  teeth  this  fact  should  be  remembered,  so  that 
injury-  to  the  internal  plate  may  be  avoided.  At  the  same  time,  no 
particular  harm  results  from  the  removal  of  a  small  portion  of  the 
outer  plate,  though  the  loss  of  any  gum  tissue  should  be  avoided  if 
possible. 

In  the  alveolar  process,  each  tooth  has  its  own  individual  process; 
as  the  tooth  develops  and  pushes  into  its  position  the  process  grows 
around  it.  These  processes  are  bound  together  by  connective  tissue, 
which  var^'  in  number  and  strength  of  union  in  different  parts  of  the 
circumference,  becoming  less  strong  in  the  upper  jaw  in  the  processes 
between  the  canine  and  second  incisor  teeth,  while  between  the  two 
first  incisors  there  are  no  bonds  of  union;  consequently  when  a  force 
is  applied  for  the  purpose  of  spreading  the  dental  arch,  the  circum- 
ference increases  by  the  stretching  of  the  connective-tissue  fibers  of 
the  alveolar  processes,  and  as  the  interpremaxillary  suture  is  the 
weakest  point,   it  naturally  opens  when  sufficient  force  is  used. 

The  interpremaxillary  suture  must  not,  however,  be  confused 
with  the  intermaxillary  which  does  not  open  (see  Fig.  74). 

Sutures  of  the  Roof  of  the  Mouth  are  seven  in  number  (see  Figs. 
71,  72,  73  and  74J. 

The  median  palatal  suture  begins  at  the  centre  of  the  free  margin 
of  the  hard  palate  or  posterior  nasal  spine,  passes  forward  between  the 
palatal  bone,  then  betw^een  the  true  maxillae  to  the  incisive  foramen, 
then  forward  between  the  premaxillse,  terminating  at  the  anterior 
nasal  spine.  It  is  divided  into  three  sections,  namely,  the  interpalatal, 
the  intermaxillary,  and  the  interpremaxillary  sutures.  There  are  four 
transverse   sutures,   two  situated  between   the   palatal   bone  and   the 


SUTURES  01'    THE  ROUE  OE   THE  MOUTH 


Fig.  71.— \ic\v  of  under  surf;ice  of  a  skull  of  about  five  and  a  half  years  of  age,  showing  the  roof  of 
the  mouth  with  the  deciduous  teeth  in  position  and  the  various  sutures. 


Fig.  72.— .Anterior  view  of  the  same  skull  as  Kig.  71,  showing  non-union  of  the  two  premaxilla;  in 

the  median  line. 


80 


THE  MAXILLM 


palatal  processes  of  the  maxillae  and  two  pass  outward  from  the  inci- 
si\e  foramen  between  the  maxillae  and  premaxillary  bones,  they  also 
pass  between  the  canine  teeth  and  the  second  incisors.  When  there  is 
a  lack  of  union  in  the  first  two  portions  of  the  median  palatine  sutures 
and  one  passing  between  the  canine  tooth  and  the  second  incisor,  there 
is  a  single  complete  congenital  cleft  palate.     If  the  two  sutures  passing 


Fig.  73. — Under  view  of  a  child's  skull  with  sutures  radiating  from  the  media  suture  toward  the 

interspace  between  the  teeth. 


between  the  canine  teeth  and  the  second  incisors  are  not  united,  there 
is  a  double  complete  congenital  cleft  palate. 

Fig.  73  is  from  a  child's  skull,  showing  more  than  the  usual  seven 
sutures,  radiating  from  the  median  suture  out  toward  the  interspaces 
between  the  teeth.  Prof.  Paul  Olbrecht'  has  also  recognized  similar 
conditions. 

•  Transactions  of  the  American  Society  of  Orthodontists  for  1908. 


STLDiEs  OF  ciJ<r.\j\  i:xtj:r.\al  si  riacj.s  of  the  skull     si 

Fig.  74  i^ixc'S  a  lair  idea  ot  the  al\C()li  of  the  ii|)i)ci'  jaw,  and  indi- 
cates the  position  of  tlic  seven  sutures  of"  the  ro(jl"  of  the  nioulh.  it 
will  be  observed  that  there  are  two  sockets  for  the  roots  (jf  the  second 
premolar  teeth.  This  is  not  usual,  thous^h  it  occurs  occasionalU'.  On 
the  rii^ht  side  thei'e  are  spaces  lor  li\-e  roots  for  the  third  molar,  which 
also  is  not  connnon. 


/'y 


/'(7/ir/xi 


Uce. 


Nmi/lo-/ifi(7j//7xillf//'^  s////jre 


^^  I//ter///(ai//(f/y  suture 


P(f?ato-um 
su/u/r 


sf/fg/re 


Fig.  74. — \'ie\v  of  the  palatal  surface  of  the  upper  jaw,  showlnij  the  aheoli  of  the  various  teeth,  and 
the  seven  sutures  of  the  roof  of  the  mouth. 


STUDIES  OF  CERTAIN  EXTERNAL  SURFACES  OF  THE 

SKULL. 

In  order  to  thoroutihly  appreciate  the  difTerences  in  the  bon\' 
anatomy  of  the  face,  it  is  necessary  to  study  skulls  and  bones  considered 
to  be  ty])ical  at  \'arious  periods  of  life. 

Front  View  of  SkuU. — Fig.  75  represents  a  front  \iew  of  a  skull, 
it  is  nearly  synmietrical,  i:)resenting  the  tyi)ical  anatomy  ot  the  exter- 
nal bony  structures  of  the  face.  There  is  but  the  slightest  \-ariation 
in   the  two  sides.      It  will  be  noticed   that   the  ui)i)er  right  first  molar 


82 


T'HE  MAXILLM 


stands  out  slightly  more  than  the  left.    The  septum  of  the  nose  is  seen 
to  be  deflected  in  the  same  direction,  and  upon  examination  of  the 


Fl(i.  75. — Anterior  view  of  the  typical  skull. 

internal  structures  of  the  nose  it  is  found  that  the  bulla  ethmoidalis 
is  enlarged  on  the  left  side,  projecting  toward  the  concavity  in  the 


STUDIES  OF  CERT  MX   EXTERXM.  SURFACES  OF   THE  SKULL       S3 

sej)tuni.     This  is  an  cxaiiiplc  of  what  niiiihl  he  taken  as  (|iiiti'  a  constant 
anatomical  hiw,   that   when   the  mouth.  i)alatc',  and  dental  arches  are 


Fig.  76. — Anterolateral  view  of  a  t\pical  skull. 

bilaterally   symmetrical,    the    outer   cranial    structures    exhibit   a   like 
condition. 


84 


THE  MAXILLM 


Fig.  76  is  an  anterolateral  view  of  a  skull  giving  a  good  idea  of  the 
occlusion  of  the  incisor,  canine,  and  premolar  teeth.  It  also  gives  a 
good  view  of  the  facial  bones  and  those  associated  with  them.  The 
inner  wall  of  the  orbit  is  well  illustrated. 

Side  View  of  Skulls. — The  following  illustrations  are  taken  from 
\'arious  side  views  of  skulls. 


GLABELLA 


4NTERIOH    NASAL 
SPINE 


PROSTHION 


qCO'?^^   ,-J^inion 


Fig.  77. — Side  view  of  typical  skull.    According  to  the  present  nomenclature  the  bone  marked  malar 
should  be  zygoma  and  that  zygoma  should  be  zygomatic  arch. 

Fig.  77  shows  a  side  view  of  a  typical  Caucasian  skull  (see  mandible 
in  Fig.  2,  and  base  of  skull  in  Fig.  90)  which  has  been  taken  as  the  foun- 
dation for  nearly  all  studies  of  the  face.  The  teeth  are  in  typical 
alignment,  shape,  and  occlusion. 

Fig.  78  (see  Mandible  in  Fig.  66,  base  of  skull  in  Fig.  91)  is  of  a  dif- 
ferent character.  It  is  taken  from  the  skull  of  one  of  the  West  African 
triljes.  The  skull  would  be  classified  by  nearly  all  as  prognathous. 
If,  however,  this  man  had  lived  until  all  of  his  teeth  and  their  alveolar 
processes  had  been  lost,  it  is  doul)tful  if  the  jaws,  especially  the  lower 
one,  would  be  considered  i)rognath()Us. 


SriDniS  ()!■   CI'.RTMX  EXTEKXAI.  SVRfACILS  OF   THE  SKLI.L       85 


^Uv 


^Qjlj^^ 


Fig.  78. — Side  view  of  a  West  African  skill 


Fig.  79. — Side  view  of  a  skull  belonging  to  a  person  of  mixed  races 


86 


THE  MAXILLA 


Fig.  79  (see  Mandible  in  Fig.  7,  base  of  skull  in  Fig.  92)  is  made 
from  a  rather  peculiar  specimen.  In  this  instance  the  two  jaws  are 
abnormally  forward  of  the  typical  position.  The  cranial  portion  in 
itself  is  not  of  a  prognathous  character,  although  the  basilar  process 
of  the  occipital  bone  is  longer  than  in  typical  skulls. 

Fig.  80  (see  Mandible  in  Fig.  8,  base  of  skull  in  Fig.  94)  is  made 
from  a  heavy  skull,  with  unusually  large,  strong  jaws  and  heavy  teeth, 
which  are  in  fairly  good  occlusion,  except  that  the  left  second  incisors 


Fig.  80. — Side  view  of  a  heavy  skull.     (See  mandible,  Fig.  8;  base  of  skull,  Fig.  94.) 


are  a  little  out  of  place.  The  extraordinary  size  of  the  jaws  and  teeth 
produces  a  general  appearance  of  prognathism,  but  the  position  of  the 
teeth  and  their  processes  does  not  carry  out  the  idea. 

Fig.  8 1  is  a  side  view  of  a  Chinese  skull,  showing  general  roundness. 
On  the  left  side  there  is  an  impacted  lower  third  molar;  in  the  upper 
jaw  of  the  same  side  there  is  no  evidence  that  the  third  molar  ever 
developed. 

Fig.  82  is  a  side  view  of  a  skull  (see  base  of  skull  in  Fig.  96).  The 
occlusion  of  the  six  molars  and  the  two  premolars,  is  fairly  good,  but 


STL' DIES  OF  CKRTAIX  KXTKR.XAL  SLRl-ACKS  OF   THE  SKULL      87 


Fig.  81. — Side  view  of  a  Chinese  skull.     (See  base  of  skull,  Fig.  95.) 


Fig.  82. — Side  view  of  a  skull.      (See  base  of  skull,  Fig.  96;    also  mandible,  Fig.  10.) 


88 


THE  MAXILLM 


the  rest  of  the  teeth  are  not  in  proper  aHgnment,  or  occlusion,  and  there 
is  an  open  bite. 

The  Base  and  the  Pharyngeal  Dome  of  Nine  Skulls. — In  these 
studies  the  centre  of  the  anterior  border  of  the  foramen  magnum  (the 
basion)  has  been  chosen  as  a  fixed  point  from  which  to  make  measure- 
ments. 

The  first  is  taken  from  the  cutting  edge  of  the  incisor  teeth  to  the 
free  border  of  the  hard  palate. 

The  second  measurement  is  from  the  free  edge  of  the  hard  palate 
to  the  anterior  border  of  the  foramen  magnum. 

The  third  measurement  is  from  the  anterior  border  of  the  foramen 
magnum  to  a  vertical  line  at  the  posterior  part  of  the  skull  at  the 
junction  of  the  sagittal  and  lambdoid  sutures. 

Fourth,  the  triangle  of  the  pharyngeal  dome  is  obtained  by  lines 
drawn  from  the  free  edge  of  the  hard  palate  (a)  to  the  anterior  border 
of  the  foramen  magnum  {b),  from  the  foramen  magnum  to  the  highest 
part  of  the  basilar  process  of  the  occipital  bone  (c)  and  from  that 
point  to  the  free  border  of  the  hard  palate  (a),  the  height  of  the  dome 
being  from  c  to  d.    (See  triangles  showing  height  of  pharyngeal  dome.) 

Base  of  Skulls  as  Illustrated. 


1st 
meas. 
mm. 

2d 
meas. 
m.m. 

Total 

(from  teeth 

to  F.  magn.) 

mm. 

3d 

meas. 
mm. 

Total 

length 

of  skull. 

mm. 

Height 

of  dome 

mm. 

Fig.  90. 

Typical  skull  .... 

58.5 

53.5 

102 

93 

195 

21.5 

"    91. 

Prognathous  skull 

69.0 

48.0 

117 

104 

221 

16.0 

"    92. 

Mixed  skulP    .... 

62.0 

48.0 

110 

95 

205 

16.0 

"    93. 

Skull 

46.0 

39.0 

85 

109 

194 

22.0 

"    94. 

Heavy  skull     .... 

64.0 

48.0 

112 

100 

212 

15.0 

"    95. 

Chinese  skull 

60.0 

40.0 

100 

94 

197 

16.5 

"    96. 

Misplaced  upper  premo- 
lars    

54.0 

38.0 

92 

105 

197 

21.0 

Prehistoric  skull^ 

59.0 

42.0 

101 

61 

162 

18.0 

Prehistoric  skull^ 

50.0 

45.0 

95 

61 

156 

23.0 

Difference  longest  to  shortest    . 

(23.0) 

(15.0) 

(32) 

(48) 

(65) 

(7.0) 

'  The  term  is  here  applied  to  a  skull  of  a  mixed  parentage. 

-  The  measurements  of  the  prehistoric  skull  of  a  cliff  dweller  were  obtained  through  the  courtesy 
of  M.  Alliot,  curator  of  the  Southwestern  Museum,  Los  .Angeles,  California. 

'See  Fig.  317.  Prehistoric  skull  from  Colorado  State  Museum,  obtained  through  courtesy  of 
Dr.  Ketcham. 


STUDIES  01'   CKRTAIX   KXTKRXAL  SLRJ-ACES  OI-    THE  SKL  LL       S9 


I  I.K.I  1 1   oi    rii.\K\'.\(;i:.\L  domk. 


43  5 

D 

Fio.  83.— Base  of  skull  (90). 


B 


A  48 

0 

Fig.  84.— Base  of  skull  (91). 


48 
D 

Fig.  85.— Base  of  skull  (92). 


39 
D 
Fig.  86.— Base  of  skull  (93). 


48 
D 
Fig.  87.— Base  of  skull  (94). 


40 
D 

Fig.  88.— Base  of  skull  (95) 


6 


Fig.  89.— Base  of  skull  (96). 


90 


THE  MAXILLA 


Fig.  90  is  an  illustration  taken  from  the  under  surface  of  a  typical 
skull.  The  relation  of  the  shape,  size  and  position  of  the  upper  jaw 
is  in  harmony  with  the  rest  of  the  skull,  and  will  be  used  in  com- 
parison with  other  illustrations  of  the  same  general  character.  The 
distance  from  the  cutting  edge  of  the  incisors  to  the  free  border  of  the 
hard  palate  is  58.5  mm.;  from  the  hard  palate  to  the  basion,  53.5  mm.; 
from  the  basion  to  the  vertical  plane  of  the  back  part  of  the  skull,  93 
mm.;  the  total  length  of  the  skull,  195  mm. 


Fig.  9U. — Under  view  or  base  of  the  skull  shown 
in  Fig.  77. 


Fig.  91. — Under  view  or  base  of  the  skull 
as  shown  in  Fig.  78. 


Fig.  91  is  made  from  a  very  prognathous  skull  (see  Fig,  78);  it  is 
a  great  contrast  to  the  one  in  Fig.  90.  The  distance  from  the  cutting 
edge  of  the  incisor  teeth  to  the  free  margin  of  the  hard  palate  is  69 
mm.,  a  difference  of  10.5  mm.  between  this  and  the  typical  skull; 
from  the  hard  jjalatc  to  the  basion  48  mm.,  a  difference  of  5.5  mm.; 
trom  the  basion  to  the  back  point  of  the  skull,  104  mm.,  a  difference 


STUDIES  OF  CKRTAIX  KXTKRXAL  SURFACES  OF  THE  SKULL      91 

of  II   mill.     Tlu'  total  Iciiiitli  of  the  skull  is  221   111111.,  a  (liffcrence  of 
26  mm. 

Fi.u.  92  is  made  from  a  skull  with  a  pr(ji;natli<jus  face  (see  Figs. 
7  and  79).  Its  measurements  are  as  follows:  From  the  cutting  edge 
(;f  the  incisor  teeth  to  the  free  margin  of  the;  hard  jjalate,  62  mm.;  from 
the  hard  palate  to  the  foramen  magnum,  48  mm.;  from  the  anterior 
border  of  the  foramen  magnimi  to  the  hack  of  the  skull.  95  mm.;  total 
length  of  skull  205  mm. 


Fig.  92. — I'nder  view  or  base  of  the  skull  as      Fig.  93. — L'nder  view  or  base  of  a  very  short  skull 
shown  in  Fig.  78.  as  shown  in  Figs.  363,  364  and  365. 

Fig.  93  is  made  from  a  very  short  skull.  The  distance  from  the 
incisor  teeth  to  the  free  border  of  the  hard  i)alate  being  46  mm.;  from 
the  hard  i)alate  to  the  foramen  magnum,  39  mm.;  from  the  basion  to 
the  back  of  the  skull,  109  mm.;  total  194  mm.  The  unusual  height  of 
the  jiharyngeal  dome  is  22  mm.,  this  measurement  indicates  the  fore- 
shortening  of  the  face;   Fig.   96   has   a    short    face    also.      The    most 


92 


THE  MAXILLM 


important  feature  of  this  picture  is  that,  on  the  left  side,  it  shows 
evidence  of  three  different  points  of  articulation  of  the  condyloid 
process  described  under  Figs.  363,  364  and  365. 

The  prehistoric  skull,  Figs.  314  and  317,  has  the  highest  pharyngeal 
dome.  22^  mm.,  and  the  shortest  skull,  156  mm.,  that  has  come  under 
the  author's  notice. 


Fig.  94. — Under  view  or  base  of  a  very  heavy 
skull  as  shown  in  Figs.  8  and  80. 


F'iG.  95. — View  of  the  base  of  a  Chinese  skull, 
showing  a  general  roundness  of  form. 


Fig.  94  is  made  from  the  base  of  a  very  heavy  skull  (see  Figs.  8  and 
80)  with  the  following  measurements;  from  the  cutting  edge  of  the 
incisors  to  the  free  border  of  the  hard  palate,  64  mm.;  from  the  hard 
palate  to  the  foramen  magnum,  48  mm.;  from  the  basion  to  the  vertical 
plane  of  the  back  of  the  skull,  100  mm.;  total  length  of  skull,  212  mm. 

Fig.  95  shows  the  base  of  a  Chinese  skull;  it  is  short  and  round, 
measuring  from  the  cutting  edge  of  the  incisor  teeth  to  the  free  margin 


ST  r  DIES  OF  C/:RT.\f.\   KXTER.\M.  ST  RF  AC  US  OF   TIIESKrFL      93 

of  llu-  hard,  palate  ()()  inni.;  from  ihc  hard  i)alalo  to  llu-  foramen 
maLiiuim,  40  mm.;  from  the  basion  lo  tlie  i)oslt'rior  i)art  of  the  skull, 
94  mm.;  total  lc'ni;th  of  the  base  of  the  skull,  197  mm. 

Fii^-.  96  is  made  from  the  under  surface  of  a  skull  in  which  there  is 
a  slight  anterior  occlusion  and  open  bite  (see  Figs.  10  and  (S2j.  The 
distance  from  the  cutting  edge  of  the  incisor  teeth  to  the  free  border 
of  the  hard   i)alate  is  54  mm.;   from   the  hard   i)alate  to   the  anterior 


Fig.  96. — I'luler  \ic'\v  of  a  skull  wIhmx'  llicre  are  two  misplaced  premolars. 


l)order  of  the  foramen  magnum,  ^cS  mm.;  from  the  basion  to  the  vertical 
l)lane  of  the  back  of  the  skull,  105  mm.;  total  length  of  the  skull,  197 
mm.  It  is  evident  that  in  this  skull  the  prin(ii)al  cause  of  anterior 
occlusion  is  the  short  distance  (onh-  92  nun.)  from  the  cutting  edge 
of  the  incisor  teeth  lo  the  hard  i)alate  and  the  foramen  magnum, 
this  is  10  mm,  shorter  than  t\pical  and  its  pharxngeal  dome  is  high. 


94  THE  MAXILLM 

It  will  be  noticed  that  two  of  the  premolars  are  out  of  line,  caused  also 
by  the  smallness  and  shortness  of  the  whole  upper  jaw.  An  additional 
cause  of  the  anterior  occlusion  is  that  the  angle  of  the  mandible  is 
unusually  obtuse,  measuring  135°.  If  correction  were  made  by  slowly 
forcing  the  upper  premolar  teeth  into  position,  it  should  lengthen  the 
arch,  which  would  assist  in  improving  the  position  of  the  anterior 
teeth.    The  fault  of  the  lower  jaw  is  at  the  angle. 

GENERAL    COMPARISONS    BETWEEN    THE    WIDTH    OF    THE 

UPPER    DENTAL    ARCH,    THE    FLOOR    OF    THE    NASAL 

FOSSA,  AND    THE    SIZE   OF   THE    MAXILLARY   SINUS. 

There  is  a  general  impression  that  a  narrow  dental  or  palatal  arch 
will  be  associated  with  a  correspondingly  narrow  nasal  floor,  but 
examination  of  a  large  number  of  skulls  does  not  confirm  this  premise. 
There  are  many  skulls  having  wide  palatal  arches  that  are  accom- 
panied by  narrow  nasal  floors,  and  also  many  skulls  in  which  the  arch 
is  narrow  while  the  floor  of  the  nose  is  wide. 

Roughly  speaking  the  upper  jaw  in  the  region  of  the  inferior  meatus 
of  the  nose  may  be  divided  horizontally  into  four  sections — two  maxil- 
lary sinuses  and  two  nasal  cavities,  if  the  latter  are  abnormally  nar- 
row, the  sinuses  will  be  comparatively  wide,  and  vice  versa,  when 
the  sinuses  are  small  or  undeveloped,  the  nasal  cavity  will  be  wide 
even  to  the  extent  of  passing  over  the  alveolar  process  and  the  roots 
of  the  teeth. 

A  few  illustrations  are  shown  in  which  the  measurements  of  the 
upper  dental  arch  have  been  taken  between  the  outer  surface  of  the 
first  molar  teeth,  and  the  width  of  the  floor  of  the  nose  measured  at  a 
corresponding  point  in  the  same  plane  (Figs.  97  and  98),  are  from 
typical  skulls,  without  any  marked  irregularities.  In  both  of  them 
the  width  of  the  floor  of  the  nose  is  about  one-half  that  of  the  dental 
arch. 

Fig.  97  is  a  vertical  transverse  section  of  a  typical  skull,  showing 
good  symmetrical  arrangement.  The  dental  arch  measured  58  mm., 
while  the  width  of  the  nasal  cavity  is  about  half,  or  29  mm.     In  other 


DENTAL  ARCH,  FLOOR  OF  XASAL  FOSSA,   MAXILLARY  SL\LS 


95 


First  nioiar  First  molar 

Fig.  97. — Vertical  transverse  section  of  typical  skull. 


.Anterior  fossa  of 
brain  case 
Crista  galli 

Orbit 

Median  wall  of 
nasal  cavity 
Ostium  maxillare 
Maxillary  sinus 
Zvgoma 
.\iaxilla 


Dental  germs 


Mandible 


Fig.  98. — Transverse  section  of  child's  head  at  birth. 


96  THE  MAXILLM 

typical  skulls  about  the  same  relative  measurements  may  be  found, 
i.  e.,  the  width  of  the  arch  is  about  twice  that  of  the  floor  of  the  nose. 

Fig.  98  is  made  from  the  skull  of  a  child  at  birth,  showing  the  same 
relative  measurements. 

Fig.  99  shows  an  arch  of  70  mm.  in  width,  while  the  floor  of  the 
nose  is  onh'  26  mm.  wide. 

Fig.  100  is  made  from  a  skull  with  a  very  narrow  dental  arch  and  a 
very  wide  floor  of  the  nose.  The  dental  arch  measures  35  mm.  The 
floor  of  the  nose,  which  should  be  27.5  mm.,  is  35  mm. 


-J"<    ^ 


X 


Fig.  99. — Wide  arch,  narrow  nose. 

Fig.  1 01  is  made  from  a  skull  with  a  very  wide  arch  and  a  narrow, 
compressed  nose.  The  measurement  of  the  arch  is  66  mm.  The 
nose  should  be  35  mm.,  but  is  only  20  mm.  It  will  be  noticed  that  the 
maxillary  sinuses  are  very  large,  which  as  before  stated,  is  usually  the 
case  where  the  nose  is  narrow. 

Fig.  102  is  made  from  a  skull  showing  a  very  narrow  arch.  The 
width  across  the  outside  of  the  second  premolars  is  but  44  mm.,  while 
the  floor  of  the  nose  measures  35  mm. 

u 

Fig.  100. — Shows  narrow  arch  and  wide  floor  of  nose. 

Fig.  103  is  from  a  vertical  transverse  section  of  a  skull  just  in  front 
of  the  first  molar  teeth,  looking  forward.  The  arch  is  of  good  width, 
though  narrow  at  the  top,  the  measurement  over  the  premolars  being 


DEXTAL   ARCIL   FLOOR  OF  XASAL  FOSSA,   MAXII.FARV  SIXi'S       97 


Fig.  101. — Shows  wide  arch  and  narrow  floor  of  nose  and  large  maxillary  sinuses. 


#i^r^ 


Fig.  102. — Shows  vcr\  narrow  arch  and  wide  nose. 


98 


THE  MAXILLA 


^^  mm.     The  floor  of  the  nose  measures  about  20  mm.,  and  the  widest 
portion  of  the  nose  is  32  mm.     There  are  unusually  large  maxillary 


Fig.  103. — Shows  unusually  large  maxillary  sinuses. 

sinuses,  with  a  correspondingly  narrow  nasal  cavity.  Before  the 
sinuses  were  cut,  each  held  one  fluidounce  and  a  quarter  (about  35 
c.c,  or  together  70  c.c).     At  the  point  of  the  section  the  two  antra 


Fic.  104. — Posterior  section  made  from  F"ig.  103. 


are  but  19  mm.  apart,  as  they  virtually  pass  under  the  nasal  cavity. 
In  the  region  of  the  first  premolar  teeth,  the  distance  between  the 
two  antra  is  al)out  13  mm. 


DENTAL  ARCH,  FLOOR  OF  XASAL  FOSSA,    MAXILLARY  SINUS       09 

Fig.   104  is  a  jjostt'rior  section  Ironi  tlit-  same  spccinu'ii  as  Fig.   103. 

Fig.  105  is  an  anterior  \  icw  of  a  xiTtical  transverse  section  showing 
small  maxillary  sinuses  and  the  nasal  ea\it>'  extending  outward  to  the 
external  ])()rtion  of  the  niaxilhe. 


Fig.  105. — -Shows  small  niaxillarv  sinus. 


Fig.  106. — Shows  nasal  cavity  extending 
over  the  alveolar  process. 


Fig.  106  is  from  a  skull  in  which  the  nasal  cavity  extends  outward 
over  the  alveolar  process  until  the  palatal  roots  of  the  first  and  second 
molars  appear  in  the  floor  of  the  nasal  cavity. 


CHAPTER  V. 
THE  MOUTH. 

The  mouth  commands  attention  by  its  great  importance  when  we 
consider  its  many  functions.  Under  normal  conditions  it  is  the  gate- 
way through  which  all  food  enters  for  the  nourishment  of  the  body. 
It  is  the  seat  of  the  organs  of  taste  and  the  workshop  wherein  are 
carried  on  the  functions  of  mastication,  insalivation,  and  the  prepara- 
tion of  food  for  the  digestive  apparatus.  It  is  also  the  portal  through 
which  more  or  less  of  the  air  received  into  the  lungs  passes.^ 

The  mouth,  or  buccal  cavit3^  occupies  the  space  between  the 
upper  and  lower  jaws  (see  Fig.  37).  It  is  divided  into  two  portions — 
the  vestibule  and  the  mouth  proper. 

The  vestibule  (see  Fig.  37)  is  a  narrow,  curved  space  having  two 
walls,  an  outer  and  inner.  The  outer  wall  consists  of  the  lips  and 
cheeks,  which  are  lined  by  mucous  membrane  containing  the  labial 
and  buccal  glands;  the  duct  of  the  parotid  gland  has  its  opening  in 
this  membrane  about  opposite  the  second  maxillary  molar.  The  inner 
wall  is  composed  of  the  teeth,  alveolar  process,  and  portion  of  the 
upper  and  lower  jaws.  The  bone  is  covered  by  a  mucoperiostium  con- 
taining small  mucous  glands;  the  upper  portion  of  the  alveolar  process 
is  covered  by  gum  tissue. 

The  mouth  proper  can  be  divided  into  roof,  sides,  floor,  and  outlet. 
The  roof  is  composed  of  hard  and  soft  palate;  the  hard  palate  has  for 
its  base  three  pairs  of  bones:  two  premaxillary,  two  palatal  processes 
of  the  maxillse,  and  the  horizontal  portions  of  the  palatal  bones;  the 
union  of  these  bones  forms  seven  sutures,  for  description  of  which  see 
page  78.  The  soft  palate  is  composed  of  several  muscles,  see  general 
anatomy  for  description. 

'  Taken  from  an  article  by  the  author  in  Musser  and  Kelly's  Hand-book  of  Practical  Treatment, 
vol.  iii,  p.  286. 


rilR  TRETII  101 

The  liard  and  s(jft  palates  are  covered  by  a  continuous  niuccnis 
membrane  extending  from  the  vestibule,  ])assing  between  the  teeth, 
to  the  free  edge  of  the  soft  pahite.  The  portion  c(jvering  the  bone  is 
in  close  relation  to  the  j:)eriosteum,  and  is  called  the  mucoperiosteum 
of  the  hard  palate.  It  is  a  strong  fibrous  co\ering  and  contains  a 
large  number  of  palatal  mucous  glands,  the  secretion  of  which  aides 
in  deglutition. 

The  sides  of  the  mouth  proper  are  composed  of  teeth,  maxillary 
and  mandibular,  the  gum  tissue,  the  alveolar  processes  of  both  jaws, 
and  all  that  portion  of  the  mandible  above  the  attachment  of  the 
mylohyoideus.  The  alveolar  process  and  the  true  bone  are  covered 
by  mucoperiosteum.  The  floor  of  the  mouth  contains  the  tongue  and 
is  composed  principally  of  the  mylohyoid  muscle.  The  outlet  of  the 
mouth  is  the  oropharyngeal  opening,  for  anatomical  description  see 
general  anatomy. 

Besides  the  general  mucous  glands  of  the  lining  of  the  mouth,  the 
ducts  of  the  submaxillary  and  the  sublingual  glands  have  their  open- 
ing near  the  frenulum  linguae. 

THE  TEETH. 

In  studying  the  anatomy  of  the  teeth,  one  finds  quite  as  many 
variations  occurring,  as  exist  in  all  of  the  other  structures  of  the  body. 
Adami  makes  the  statements  that  "there  is  no  absolute  standard  of 
either  structure  or  function  in  any  one  species,"  "every  individual 
varies  in  every  particular  from  evers'  other  individual."  It  was  also 
stated  by  the  author  in  1901,  in  the  preface  to  the  first  edition  of  this 
book  that  "there  is  doubtless  a  typical  or  typal  form  for  each  bone,  but 
it  is  not  often  found  in  nature.  If  we  were  to  photograph  a  thousand 
temporal  bones  for  example,  the  composite  of  the  entire  number  would 
properly  be  accepted  as  figuring  the  typal  temporal;"  in  the  same  way, 
if  photographs  could  be  made  of  a  thousand  molars,  the  composite 
picture  should  give  the  type  of  a  molar  tooth  which  could  be  taken 
as. standard  in  studying  that  particular  tooth;  it  follows  of  course  that 
this  "type"  can  only  be  used  as  a  basis  for  the  practical  stud>'  of  the 


102  THE  MOUTH 

variations  as  to  size,  shape,  color  of  enamel,  etc.,  which  are  presented 
by  every  individual. 

The  teeth  are  situated  in  the  mouth  at  the  commencement  of  the 
alimentary  canal.  In  man  they  are  equally  divided  into  maxillary 
and  mandibular  teeth.  They  are  of  dermoid  origin  and  commence 
development  in  earh'  embryonic  life.  The  principal  functions  are 
cutting,  masticating  and  preparing  food  for  digestion.  They  also 
assist  in  articulate  speech. 

Man  has  two  sets  of  teeth,  deciduous  and  permanent.  The  decid- 
uous set  is  composed  of  twenty  teeth  of  the  following  formula. 

DECIDUOUS  SET. 

^     .  r  Maxillary      4         „.        (2         ...        (^         r^      ■>    r,r^ 

IncisorsJ  -,      ...   '       ,         Canines  <^  „         Molars  <   .         Total,  20 

\  Mandibular  4  \  2  14 

THE  PERMANENT  SET. 

-     .         /Maxillary      4  „      .        /2         „  ,        /4  ,,  ,       /6         ^  ,  ^    .^ 

Incisors  <  , ,       ...     ,       ,  Canines^  -,         rremolars  ^   .  Molars  s   ,  lotal,  32 

I  Mandibular  4  \1  1 4  I  6 

The  eight  incisor  teeth  are  situated  in  pairs  on  either  side  of  the 
median  line  of  the  mouth,  the  upper  ones  are  in  the  incisive  or  inter- 
maxillary bone,  the  lower  ones  in  the  mandible,  these  teeth  are  known 
as  first  and  second  maxillary  and  mandibular  incisors  respectively.^ 

The  maxillary  canine  teeth  are  situated  in  the  anterior  portion  of 
the  alveolar  process  of  the  true  maxillae.  The  mandibular  canines  are 
next  to  the  second  incisors  in  the  mandible. 

The  deciduous  molars,  first  and  second,  are  posterior  to  the  canine 
teeth.  The  eight  premolars,  permanent  set,  are  situated  in  pairs 
anterior  to  the  molars,  on  either  side,  both  in  the  maxillae  and  mandible. 

The  perminent  molars,  first,  second  and  third  are  the  last  teeth 
on  either  side  in  the  maxillae  and  the  mandible  and  have  no  deciduous 
teeth  preceeding  them. 

In  a  general  way  the  anatomy  of  a  tooth  consists  of  four  parts, 
the  crown,  neck,  roots,  and  pulp. 

^  The  writer  prefers  the  nomenclature  used  by  general  scientists  and  comparatiye  anatomists, 
and  will  speak  of  first  and  second  incisors  rather  than  "central"  and  "lateral,"  "canine"  rather  than 
"cuspid"  and  "premolar,"  rather  than  "bicuspid,"  "anterior"  and  "posterior"  faces  or  cusps  instead 
of  "mesial"  and  "distal." 


TIIK   TKKTII  103 

The  crown,  in  normal  condition,  is  that  portion  extending  through 
the  gum  tissue  and  is  the  tirst  i)art  of  the  tooth  formed.  Its  (juter 
portion  is  covered  with  enamel,  the  IxxK  un<l(.'r  the  enamel  is  com- 
posed of  denlint'  w  ithin  w  hich  is  the  i)ulp  chamber,  containing  the  l)od\' 
of  the  pulp. 

The  neck  of  the  tooth  is  the  constricted  jiortion  l)etween  the  crown 
and  the  root,  it  is  at  this  point  that  cementum  of  the  root  joins  the 
enamel  of  the  crown. 

The  root  of  the  tooth  is  that  i)orti()n  w  hich  is  held  within  the  al\  eolar 
process  by  the  assistance  of  membranous  tissue.  Its  outer  portion  is 
covered  by  cementum  under  which  is  a  continuation  of  the  dentine  of 
the  crown.  The  number  of  roots  varies  according  to  the  teeth;  single 
crown  teeth  such  as  incisors  and  canines  usually  have  but  (jne  root, 
though  there  are  exceptions  to  this  rule,  especially-  in  the  canines. 
The  roots  of  the  other  teeth  generally  follow  the  number  of  cusi)s  in 
the  crown. 

The  pulp  is  that  portion  of  the  tooth  found  within. the  pulp  chamber 
and  the  pulj)  canals.  Its  shape  generally  at  maturity  is  a  miniature 
of  the  crown  and  roots. 

Anatomy  of  the  Permanent  Teeth. — Incisors. — Eight  in  number. 
The  four  maxillary-  incisors  are  situated  in  the  intermaxillary  bone, 
two  on  either  side  of  the  median  line  and  are  named  right  and  left, 
first  and  second  incisors,  they  are  so  similar  that  one  description  ^\'ill 
answer  for  both. 

The  crowns  are  somewhat  wedge-  or  chisel-shaped,  being  much 
wider  at  the  cutting  edge  than  at  the  neck  and  are  somewhat  thicker 
at  the  base,  sloping  to  a  thin,  sharp-cutting  edge  for  biting  and  cutting 
the  food,  when  these  teeth  are  first  erupted  the  edges  are  indented, 
but  the\'  are  soon  worn  smooth. 

The  labial  face  of  the  crown  is  slightly  con\ex  trom  the  cer\ical 
margin  to  the  cutting  edge,  and  also  in  a  transverse  direction.  It 
usually  has  two  \ery  shallow  depressions  running  from  the  cer\ical 
margin  to  the  cutting  edge  of  the  tooth  which  dixides  the  surface  into 
three  slight  lobes.  Where  the  labial  surface  joins  the  neck  it  is  semi- 
circular in  form. 


104  THE  MOUTH 

The  cutting  edge  is  not  quite  at  a  right  angle  with  the  longitudinal 
axes  of  the  tooth.  The  anterior  corners  are  slightly  pointed  and  the 
cutting  edge  slopes  backward  and  slightly  upward  joining  the  lateral 
sides  of  the  crowns  in  a  curved  manner.  This  curve  is  more  marked 
in  the  second  incisors  than  in  the  first. 

The  palatal  face  is  narrower  than  the  labial,  which  allows  the  better 
adaptation  of  the  teeth  to  the  dental  arch.  This  face  is  markedly  con- 
cave, both  in  length  and  width;  very  often  there  is  an  increase  in  size 
near  the  upper  margin,  making  a  small  cusp  known  as  a  cingulum; 
between  this  and  the  cutting  edge  there  is  often  a  small  pit  which 
makes  a  predisposing  cause  of  decay,  this  is  more  frequent  in  the 
second  incisor  than  in  the  first.  Where  the  palatine  face  joins  the 
neck  of  the  tooth  it  is  convex  in  form. 

The  anterior  (proximal)  face,  or  that  portion  facing  the  incisor  of 
the  opposite  side,  is  triangular  in  shape.  The  base  of  which  is  concave 
and  joins  the  neck  of  the  tooth,  from  the  labial  and  palatine  margin 
of  this  face  the  lines  of  the  wedge  slope  toward  each  other,  forming 
a  prominent  point,  this  face  is  convex  in  both  directions. 

The  posterior,  lateral  face  is  very  similar  to  the  anterior  face,  except 
it  is  shorter  and  more  convex,  terminating  in  a  rounded  corner. 

The  cervical  margin  of  the  labial  and  palatine  faces  of  the  crown  is 
convex  while  the  lateral  portion  is  concave. 

The  first  incisor  is  larger  than  the  second,  and  is  more  regular  in 
shape.  The  second  incisor  is  more  apt  to  be  abnormal  in  shape.  It 
is  occasionally  lacking  in  the  denture,  and  on  the  other  hand,  there 
may  occasionally  be  a  third  incisor  (see  Fig.  340). 

The  neck  of  the  incisors  is  somewhat  constricted,  showing  the 
union  of  the  cementum  covering  the  root,  with  the  enamel  covering 
the  crown.  In  a  transverse  section  the  neck  is  rather  oval  in  outline 
with  the  labial  surface  a  little  wider  than  the  palatal.  The  lateral 
edge  slightly  overlaps  the  root,  which  causes  a  better  fitting  of  the 
tooth  in  the  gums. 

The  root  of  the  incisor  is  long,  single  and  cone-shaped,  somewhat 
flattened  transversely.  The  root  of  the  first  incisor  is  larger  than  that 
of  the  second.  The  root  of  the  second  is  more  flattened  and  is  liable 
to  be  slightly  curved  backward  near  the  apex. 


TIIR  TEETII  10.-) 

The  pulp  chamber  and  its  pulj)  canals  generally  resemble  the  tcxjth 
in  miniature,  though  in  some  cases  a  c()mi)ressecl  root  may  ha\e  two 
or  more  pulp  canals  passing  to  the  apices  of  the  roots.  This  is  imi)or- 
tant  to  know  when  diseased  canals  are  to  be  treated.  Another  inijjor- 
tant  feature  of  the  pulp  chamber  of  a  tooth  is  that  it  is  comparatively 
large  in  youth,  becoming  smaller  as  age  advances. 

Canine  Teeth. — Four  in  number,  two  maxillary-  and  two  mandib- 
ular. The  two  maxillar}' canines  are  situated  in  the  anterior  portion  (A 
the  aheolar  i)rocessof  the  true  maxillar\-  bone,  posterior,  laterally,  tcj  the 
second  incisors.  The  architectural  features  of  the  canine,  together  w  ith 
its  firm  osseous  surrounding  make  it  a  very  important  and  powerful 
tooth.  Its  root  is  longer  and  stronger  than  that  of  any  other  tooth. 
Its  size  and  position  make  it  of  great  importance  to  the  facial  expres- 
sion, it  assists  in  producing  the  canine  eminence  also  the  canine  fossa 
of  the  facial  bones.  Its  loss  is  indicated  by  depressed  lines  of  the 
face  which  generally  indicate  "old  age."  This  tooth  is  very  seldom 
omitted  in  its  development,  though  it  is  very  often  misplaced.  It  is 
the  opinion  of  the  writer  that  it  is  the  second  tooth  in  frequency  of 
impaction.  The  third  mandibular  molar  being  the  first.  The  canine 
is  usually  erupted  after  the  second  incisor  and  first  premolar,  and  its 
normal  position  is  often  encroached  upon  by  these  teeth.  The  crown 
of  the  canine  tooth  has  four  irregular,  flattened  faces. 

The  labial  face  is  spear-shaped  with  base  joining  the  neck  of  the 
tooth  in  a  convex  form.  Passing  from  the  base  there  is  a  prominent 
ridge  extending  to  the  point  of  the  crown  which  divides  the  face  into 
two  unequal  parts,  the  anterior  portion  being  narrower  than  the  pos- 
terior; on  each  side  of  the  ridge  is  a  slight  depression  dividing  the  labial 
surface  of  the  tooth  into  three  lobes,  the  middle  lobe  being  much  the 
largest. 

The  palatal  face  is  spear-shaped  and  is  beveled  from  the  base  to 
the  cutting  edge.  At  the  centre  of  the  base  there  is  usually  a  cingulum 
from  which  a  ridge  extends  to  the  cutting  edge,  dividing  the  face  into 
two  portions.  There  are  also  two  lobes  or  elevations  on  the  outer 
and  inner  margins  of  the  face,  which  with  the  central  ridge  forms  a 
depression  on  each  side. 


lOi;  THE  MOUTH 

The  anterior  and  posterior  faces  are  similar  to  those  of  the  first 
incisor.  Where  the  posterior  edge  joins  the  cutting  edge  there  is  con- 
siderable enlargement,  making  the  neck  appear  narrow. 

The  cutting  edge  of  the  crown  tapers  to  a  blunt  point  which  pro- 
jects somewhat  below  the  other  teeth  and  is  divided  into  two  unequal 
parts;  the  anterior,  which  is  the  shorter,  occludes  with  the  posterior 
surface  of  the  mandibular  canine;  the  posterior  portion  occludes  with 
the  anterior  surface  of  the  first  mandibular  premolar. 

The  neck,  in  transverse  section,  is  a  flattened  oval,  the  curvature 
on  the  labial  surface  being  larger  than  on  the  lingual. 

The  root,  which  is  longer  and  stronger  than  those  of  the  other  teeth 
is  a  flattened  cone,  with  a  slight  curve  pointing  backward. 

The  pulp  and  its  canals  generally  resemble  the  tooth  in  miniature. 

Premolar  Teeth. — The  premolar  teeth  are  eight  in  number,  four 
in  the  maxillse  and  four  in  the  mandible. 

The  maxillary  premolars  (upper  bicuspids)  are  posterior  to  the 
canine  teeth  and  are  seldom  omitted  in  their  development,  occasionally, 
however,  while  the  deciduous  molar  may  develop  normally,  the  pre- 
molar that  should  follow  it,  will  not  be  present  (see  Fig.  328).  There 
are  several  cases  on  record  where  three  premolars  have  been  formed 
on  each  side  of  the  maxilla  and  mandible,  and  one  case  has  come  under 
the  writer's  observation  where  there  are  four  premolars  on  each  side 
of  the  mandible  (see  Figs.  343  and  344). 

The  premolar  teeth  are  sometimes  spoken  of  as  double  teeth,  but 
their  appearance  is  more  like  two  canines  fused  together. 

The  first  maxillary  premolar  is  usually  larger  than  the  second. 

The  crown  is  cuboidal  and  has  five  faces,  the  buccal,  palatal, 
anterior,  posterior,  and  morsal. 

The  buccal  face  is  very  similar  to  that  of  the  canine  tooth.  It  is 
spear-shaped,  with  the  base  joining  the  neck  of  the  tooth  in  a  curved 
form. 

Passing  fr(jm  the  base  there  is  a  prominent  ridge  extending  to  the 
point  of  the  spear-shaped  cusp  which  divides  this  face  into  two  unequal 
parts,  the  anterior  portion  being  the  narrowest;  on  each  side  of  the*, 
ridge  there  is  a  slight  depression,  making  three  lobes,  the  middle  lobe 
being  much  the  largest. 


THE  TElVril  107 

Tlu'  ])alalal  fact'  is  \  cry  similar  lo  the  hiiccal,  (liffLTin^  in  size, 
l)eini;  narnnvLT  and  sliorlcr. 

The  anterior  and  jKJsterior  laces  are  i;enerall>  similar,  bein^  convex 
on  the  ui)i)er  portion  of  the  face  and  slii;htly  concave  near  the  neck, 
these  faces  slope  inward  on  i)assini;  toward  the  neck,  making  the 
crown  much  narrower  at  this  point,  and  helping  to  make  an  inverted 
\'-shaped  space  between  the  premolar  and  the  adjoining  teeth. 

The  morsal  face  consists  of  two  cusps  with  two  connecting  ridges, 
anterior  and  posterior;  betw^een  the  labial  and  palatal  edges  of  the 
cusps,  there  is  a  sulcus  somewhat  in  the  f(jrm  of  a  letter  H.  This  for- 
mation makes  a  weak  place  in  the  enamel  of  the  crown,  which  gives  a 
predisposing  cause  of  caries. 

The  neck  is  a  compressed  oval  somewhat  wider  on  the  buccal  face. 

The  first  premolar  usually  has  two  roots.  The  root  of  the  second 
premolar  nvdy  be  bifurcated,  but  it  is  usually  single,  with  two  i)ulp 
canals;  sometimes  there  is  a  bifurcation  near  the  apex. 

The  pulp  chamber  and  its  pulp  canals,  under  ordinary  circum- 
stances, is  a  miniature  of  the  premolar  tooth. 

The  Second  Maxillary  Premolar. — The  description  of  the  first 
])remolar  will  answer  for  the  second,  except  that  the  second  is  usually 
smaller,  with  but  one  root,  but  it  must  be  remembered  in  the  treatment 
of  this  tooth  that  occasionally  it  may  have  two  roots  and  also  that 
the  first  i)remolar  may  have  but  one  root. 

Molar  Teeth.— The  molar  teeth  are  twelve  in  number,  six  in  the 
maxilla  and  six  in  the  mandible.  These  teeth  have  no  i)redecessors 
as  have  the  other  twenty  permanent  teeth.  They  are  situated  on  each 
side  of  both  jaws,  and  with  more  or  less  variation,  erupt  at  different 
periods.  The  first  molars  about  the  sixth  vear,  the  second  from  the 
twelfth  to  thirteenth  year,  and  the  third  from  the  seventeenth  to  the 
twenty-third  vear  or  even  later.  The  first  molar  takes  its  position  in 
the  posterior  portion  of  the  alveolar  process;  as  the  jaws  develop  they 
usually  make  room  for  the  other  two  molars.  At  times  the  jaws  do 
not  seem  to  grow  sufticientl}'  to  allow  proper  eruption  to  take  place; 
in  these  cases,  the  third  molar  is  sometimes  impacted  or  misplaced. 
It  also  occasionally  happens  that  the  third  molar  does  not  develop  at 


108  THE  MOUTH 

all;  again,  there  may  be  a  rudimentary  fourth  molar  sometimes  called 
a  supernumerary  third  molar. 

When  these  teeth  are  in  topical  occlusion,  the  six  mandibular  molars 
articulate  with  the  maxillary  molars  and  the  posterior  half  of  the 
maxillary  second  premolars.  As  they  are  situated  near  the  fulcrum 
of  the  mandibular  articulation,  and  are  in  close  proximity  to  the  attach- 
ment of  the  powerful  muscles  of  mastication,  they  are  in  position  to 
receive  the  full  force  of  these  muscles  for  crushing:  and  grinding  the 
food. 

The  maxillary  molar  teeth  are  situated  in  the  alveolar  process 
immediately  below  the  maxillary  sinus.  In  the  Caucasian  race  the 
alveolar  process  is  shallow,  the  roots  of  the  molar  teeth  are  spread 
apart  and  pass  into  the  outer  and  inner  walls  of  the  sinus  (see  Figs.  37 
and  97).  The  molar  teeth  in  this  position  are  liable  to  produce  patho- 
logical conditions  in  the  sinus.  In  the  lower  type  of  man  the  alveolar 
processes  are  much  deeper,  and  the  molar  roots  do  not  enter  the  walls 
of  the  sinus  (see  Fig.  200). 

The  crowns  are  somewhat  cuboidal  in  shape,  with  five  faces,  the 
buccal,  palatal,  anterior,  posterior,  and  morsal. 

The  buccal  face  is  nearly  twice  the  size  of  that  of  the  second  pre- 
molar, its  general  appearance  is  that  of  two  fused  premolar  teeth  hav- 
ing the  cusps  very  marked.  The  anterior  buccal  cusp  was  called  by 
Harrison  Allen  the  "canine  cusp."  In  his  "Facial  Region"  he  also 
stated  that  "Since  the  cusps  exist  before  the  roots,  the  latter  may  be 
said  to  be  conformed  to  the  cusps.  So  that  to  every  cusp  there  is  a 
tendency  to  form  a  distinct  root.  It  is  best,  therefore,  to  study  the 
teeth  by  their  cusps."  ^  Following  this  plan,  the  cusps  indicate  the 
general  character  of  the  tooth,  whether  it  be  a  single,  double  or  multi- 
cusped  tooth. 

First  Maxillary  Molar. — As  said  before,  the  buccal  face  has 
the  appearance  of  two  premolars  fused  together.  The  centre  of  this 
face  is  convex,  sloping  as  it  approaches  the  neck  of  the  tooth.  From 
just  below  the  centre,  a  perpendicular  groove  commences,  deepening 
as  it  passes  toward  the  morsal  edge,  thus  making  an  anterior  and  pos- 

'  J.  B.  Lippincott  Co.  Press,  p.  IH. 


THE  TEETH  109 

terior  buccal  surface  of  the  cusj),  the  cdi^cs  of  wliich  iiiccl  the  anterior 
and  posterior  surfaces  in  a  ciirxed  manner. 

The  i)ahital  face  is  conxex.  ha\  ini;  a  small  fissure  about  one-third 
from  the  posterior  edge,  i)assini;  downward  to  the  occluding  surface 
of  the  tooth,  which  joins  the  posterior  fissure  of  the  morsal  face. 

The  anterior  and  posterior  faces  are  generally  convex  in  both 
directions,  sloping  downward  to  the  masticating  edge  in  a  rounded 
manner  and  curx  ing  upward  toward  the  neck  of  the  tooth. 

The  morsal  face  is  divided  into  four  cusps.  The  anterior  buccal, 
or  canine  cusp,  is  ver\-  much  the  shape  of  a  canine  tooth,  hence  the 
name;  the  posterior  buccal,  or  molar  cusp,  is  usually  about  the  same 
size,  though  not  quite  so  pointed.  The  anterior  palatal,  or  premolar 
cusp,  is  very  much  larger  and  more  rounded  than  the  canine  cusp. 
The  posterior  palatal  cusp,  the  cingule,  is  small  and  forms  a  rather 
prominent  corner  or  pillar  to  the  tooth.  Between  the  three  main  cusps 
there  is  an  irregular  surface ;  between  the  two  palatal  cusps  is  a  deep 
sulcus  which  forms  a  predisposing  place  for  caries. 

The  neck  in  transverse  section  is  rhomboidal  in  shape,  with  rounded 
corners;  the  buccal  face  is  wider  than  the  palatal  as  it  forms  the  base 
for  the  two  roots.  The  palatal  face  of  the  neck  is  more  rounded  than 
the  buccal  and  forms  the  base  for  the  large  palatal  root,  which  is 
usually  single. 

The  roots  are  three  in  number,  two  buccal  and  one  palatal,  they 
are  usually  well  separated  at  their  upper  ends.  The  anterior  buccal 
root  is  rather  flattened  and  may  have  two  pulp  canals  within  it.  The 
posterior  buccal  root  is  rounded,  usually'  having  but  one  pulp  canal. 
The  palatal  root  is  larger  and  rounded,  having  but  one  pulp  canal, 
which  is  usually  straight  and  large  as  compared  with  the  others,  and 
therefore  of  easy  access. 

The  second  maxillary  molar  is  usualK'  similar  to  the  first, 
when  differences  exist,  it  is  in  the  shape  of  the  crown  and  the  diver- 
gence of  the  roots.  The  crown  is  somewhat  smaller  than  the  first 
molar  and  is  often  triangular  in  outline.  The  cingulum  is  generally 
much  smaller  and  consequently  the  premolar  (anterior  palatal)  cusp 
is  larger,  which  gives  a  large,  smooth  surface  to  the  palatal  face.    The 


110  ■  THE  MOUTH 

fissure  between  the  cingulum  and  the  premolar  cusps  is  not  so  deep, 
and  consequently  not  so  prone  to  decay.  The  anterior  and  posterior 
faces  differ  from  each  other;  the  anterior  face  is  usually  more  flat 
while  the  posterior  face  is  quite  oval,  especially  when  the  third  molar 
is  small  or  missing',  in  the  latter  case  it  is  liable  to  be  quite  rounded  as 
a  "finishing  tooth." 

The  neck  is  similar  to  the  neck  of  the  first  molar,  varying  only  in 
proportion  to  the  various  shapes  of  the  crowns. 

The  roots  are  generally  the  same  in  number  though  varying  in  size, 
they  are  also  generally  close  together,  due  to  the  fact  that  the  pos- 
terior root  of  the  first  molar  is  occupying  more  or  less  of  the  space 
which  the  anterior  root  of  the  second  molar  might  have  taken. 

The  size  of  the  maxillary  sinus  may  influence  the  position  and  shape 
of  the  roots  of  the  molar  teeth  (see  Fig.  199). 

The  third  maxillary  molar  is  more  varied  in  its  shape  than  any 
of  the  other  maxillary  teeth;  it  may  be  large  or  small,  may  have  a 
small  cingulum  cusp  with  a  single  root  (called  a  peg  tooth),  or  it  may 
have  many  cusps  with  a  corresponding  number  of  roots,  which  may 
be  straight  or  curved. 

If  the  pulp  becomes  diseased  it  is  most  difficult  to  treat,  and  for 
this  reason  the  maxillary  third  molar  has  been  classed  by  some  as  the 
pathological  tooth  of  the  mouth. 

Mandibular  Teeth. — The  mandibular  teeth  are  the  active  organs  of 
mastication,  in  as  much  as  they  are  fixed  in  the  mandible  which  is  acted 
upon  by  the  temporalis,  masseter,  pterygoideus,  externus  and  internus 
muscles  (see  Fig.  300) .  These  muscles  give  the  lower  jaw  power  of  protru- 
sion, retrusion,  and  side-to-side  movement  (see  Mandibular  Articulation, 
page  68).  which  in  turn  together  with  the  depressor  muscles  of  the 
mandible,  enable  the  teeth  to  cut,  tear,  and  grind  food.  The  loAver 
anterior  teeth  come  in  contact  with  the  upper  fixed  teeth,  striking  the 
cutting  edge,  then  coming  against  the  under  concave  surface  of  the 
upper  anterior  teeth  in  a  general  motion  similar  to  that  of  a  pair  of 
shears,  provided  the  upper  blade  of  the  shears  were  fixed. 

The  posterior  mandibular  teeth  meet  the  upper  posterior  teeth  in 
both  grinding  and  crushing  motions. 


THE   TRETH  HI 

The  two  lirst  rii;hl  and  k-ft  incisors  are  situated  on  either  side  ot 
the  sxniplnsis.  'lMie\-  are  the  smallest  teeth  in  tlie  nicuth.  Tlie  first 
nia\illar\  incisors  are  much  wider,  as  the>'  not  only  cover  the  first 
mandii)ular  incisors,  but  extend  over  one-half  the  second  mandibular 
incisors,  thus  "  breaking  the  joint."  This  breaking  of  the  joint  is  carried 
on  between  the  maxillar\-  and  mandibular  teeth  throughout  the  balance 
of  the  jaws  until  the  third  molars  are  reached.  The  third  ma\illar\ 
molar  occludes  only  with  the  third  mandibular  molar. 

The  crown  of  each  first  mandibular  incisor  has  four  faces  and  a 
cutting  edge. 

The  labial  face  is  slighth'  conxex  in  both  directions.  It  is  broadest 
at  the  top  or  cutting  e(\'ge,  w  hich  is  straight. 

The  face  becomes  narrow  toward  the  cer\ical  portion,  whicdi  is 
con\ex. 

The  lingual  face  is  slightly  convex  from  side  to  side  and  concave 
perpendicularly. 

The  lateral  faces  are  concave  and  wedge-shaped  with  the  point  of 
the  wedges  at  the  top  or  cutting  edge  and  the  base  at  the  neck  of  the 
tooth. 

The  neck  is  small,  and  in  a  transverse  section,  is  a  slightly  com- 
pressed oval. 

The  root  is  not  so  long  as  the  second  incisor  root,  and  is  usually 
straight  and  somewhat  flattened  with  but  one  pulp  canal. 

The  iHilp  chamber  and  its  canal  is  of  the  same  shape  as  the  tooth, 
onh-  \er>-  much  smaller. 

The  second  mandibular  incisors  are  similar  to  the  first  only 
somewhat  longer  and  larger.  The  cutting  edge  is  much  wider,  and  the 
posterior  face  tapers  into  the  neck  of  the  tooth.  The  root  is  of  the 
same  general  outline  as  the  first  incisor,  only  larger  and  longer. 

The  mandibular  canine,  right  and  left,  is  similar  to  the  maxillary 
canine,  the  architectural  plan  is  on  the  same  general  lines  with  the 
strongest  point  at  the  neck  (see  transverse  section.  Fig.  114).  This 
tooth  is  the  least  prone  to  decay  of  all  the  teeth. 

The  crown  has  four  faces.  The  labial  face  is  convex  both  horizon- 
tally and  vertically;  it  is  broader  at  the  cutting  edge,  which  is  divided 


112  THE  MOUTH 

into  two  portions  like  a  spear  point,  the  posterior  portion  being  the 
longest;  occasionally  there  are  two  slight  grooves  passing  vertically 
from  the  cutting  edge  to  the  base  of  the  crown  which  is  convex. 

The  lingual  face  is  in  a  general  way  concave  from  the  cutting  point 
to  the  neck;  there  is  a  slight  central  ridge  curving  to  a  groove  on  each 
side  of  the  tooth. 

The  anterior  face  (mesial)  is  broader  than  the  posterior.  The  pos- 
terior face  is  wedge-shaped  with  the  base  at  the  neck.  Commencing 
at  the  cutting  edge  the  face  slopes  toward  the  neck,  which  is  narrow, 
leaving  a  considerable  space  between  the  canine  and  the  first  premolar. 

The  neck  (see  Fig.  114)  is  much  larger  than  that  of  any  of  the  teeth 
except  the  molar;  it  is  wider  at  the  labial  surface  than  at  the  lingual. 

The  root  is  the  longest  of  any  of  the  lower  teeth,  sometimes  extend- 
ing below  the  general  line  of  the  mandibular  canal  (see  Fig.  161). 
Occasionally  this  tooth  has  two  roots  and  at  times  in  the  single  root 
there  may  be  two  pulp  canals. 

Mandibular  Premolars. — The  first  mandibular  premolars  are 
situated  just  posterior  to  the  canines,  they  are  usually  smaller  than  the 
second  premolars.  The  crown  of  each  tooth  has  five  faces;  the  buccal 
face  is  similar  to  that  ot  the  canine  and  is  named  by  Harrison  Allen, 
the  canine  cusp;  it  has  a  slight  ridge  passing  from  the  spear  point 
down  to  the  base,  which  is  convex  and  there  are  two  slight  grooves 
on  each  side  of  the  ridge  which  might  be  said  to  divide  the  face  into 
three  lobes. 

The  lingual  face  is  convex  horizontally  and  nearly  straight  perpen- 
dicularly, sloping  to  a  narrow,  convex  base.  The  lateral  faces  are  also 
convex  horizontally,  they  slope  inward  toward  the  centre  of  the  tooth, 
making  the  neck  narrow,  with  inverted  Y-shaped  spaces  between  it 
and  the  canine  and  the  second  premolar. 

The  morsal  face  varies  in  different  teeth.  There  are  usually  two 
marked  cusps:  the  canine  cusp  on  the  buccal  side,  and  the  premolar 
on  the  lingual  side;  running  from  the  outer  and  inner  faces  of  the 
cusps  are  ridges  of  enamel,  somewhat  elevated  in  the  centre,  forming 
smaller  cusps;  between  these  four  cusps  are  two  pits  or  sulci  which 
make  predisposing  points  for  caries. 


rilK  TEETH  113 

The  iK'ck  is  a  c()nij)rcssc(l  ()\al,  smaller  im  the  iin.uuai  cdi^c,  tlian  on 
the  buccal. 

The  root,  iisualh-  sinj^lc.  is  lon^,  flattcnerl  and  comparatively 
straight,  but  at  times,  as  the  number  of  cusps  indicates,  the  root  may 
be  composed  of  two  or  more  divisions. 

The  i)ulp  chaml)er,  and  its  canals,  in  earl\-  life,  is  generall>'  a  minia- 
ture of  the  tooth,  the  number  of  pulj)  canals  corresponding  to  the 
number  of  cusps. 

The  second  mandibular  premolars  arc  situated  between  the  first 
premolars  and  the  first  molar  teetii.  In  a  general  way  the  description 
of  the  first  premolar  will  answer  for  the  second  except  that  it  is  usualK' 
larger. 

The  morsal  face  of  the  crown  differs  somewhat  in  the  arrangements 
of  the  cusps,  in  some  cases  it  might  be  called  tricusped. 

The  neck  of  the  tooth  is  a  little  larger  than  that  of  the  first  premolar. 

The  root  is  usually  single,  but  occasionally  it  is  flattened  and 
di\ided.     In  rare  cases  there  are  three  roots  (see  Fig.  122). 

The  pulp  chamber  is  practically  the  same  except  that  there  may 
be  several  pulp  canals. 

Mandibular  Molar  Teeth. — The  mandibular  molar  teeth  are  sit- 
uated in  the  posterior  portion  of  the  body  of  the  mandible  immediateh' 
over  the  canal  which  contains  the  mandibular  nerve  and  vessels;  any 
disturbance,  pathological  or  mechanical,  in  this  region,  is  liable  to 
cause  serious  conditions,  such  as  impacted  teeth,  neuralgia,  reflex 
nervous  disturbances,  sometimes  only  local,  but  often  reaching  into 
the  general  nervous  system. 

These  teeth  have  no  predecessors  and  erupt  one  after  another  as 
the  body  of  the  bone  grows  sufificienth-  to  make  room  for  them.  When 
this  room  is  not  adequate,  the  third  molar  or  e\en  the  second  molar 
is  liable  to  become  impacted  or  misplaced,  causing  more  or  less  serious 
complications. 

The  first  mandibular  molar  is  situated  posterior  to  the  second  pre- 
molar. In  correct  occlusion,  it  articulates  with  the  posterior  portion 
of  the  morsal  face  of  the  second  maxillary  premolar  and  the  anterior 
portion  of  the  morsal  face  of  the  first  maxillarA-  molar. 

8 


114  THE  MOUTH 

The  crown  is  of  an  irregular  ciiboidal  form,  with  a  greater  width 
anteroposteriorally  than  buccohngually.  It  has  five  faces:  buccal, 
palatal,  anterior,  posterior,  and  morsal. 

The  buccal  face  is  usually  convex  in  all  directions;  it  is  divided  into 
three  columns  by  two  rather  deep  grooves,  the  buccal  and  posterior. 
The  buccal  groove  occasionally  passes  down  through  the  face,  but 
usually  terminates  midway  in  a  pit,  which  acts  as  an  inducement  for 
decay,  the  morsal  edge  is  divided  into  three  points,  which  help  to  form 
three  buccal  cusps. 

The  lingual  face  is  rounded  and  smooth.  There  are  seldom  any 
fissures  on  this  surface  which  make  it  quite  free  from  caries.  The 
morsal  edge  terminates  in  two  points,  which  assist  in  forming  two 
lingual  cusps,  the  fissures  between  these  two  elevations  is  somewhat 
prone  to  decay. 

The  anterior  and  posterior  faces  are  flattened  perpendicularly,  the 
upper  border  is  convex  and  as  the  face  passes  downward  toward  the 
neck  it  becomes  flattened.  These  faces  are  inclined  inward,  making 
an  inverted  V-shaped  space  between  this  molar  and  the  premolar, 
also  between  the  first  and  second  molar. 

The  morsal  face  is  the  largest  face  of  any  of  the  teeth  and  is  divided 
into  five  cusps,  two  buccal,  two  lingual  and  a  posterior  cusp.  The 
anterior  buccal  cusp  is  very  much  the  shape  of  the  canine  crown,  and 
is  the  largest  and  most  prominent  cusp.  The  median  buccal  cusp  (the 
molar  cusp)  is  usually  somewhat  smaller  than  the  canine  cusp.  The 
two  inner  or  lingual  cusps  are  nearly  the  same  size.  The  fifth  cusp, 
which  is  in  the  posterior  portion  of  the  crown,  is  small  and  sometimes 
spoken  of  as  the  cingulum  of  the  tooth. 

The  fissures  pass  in  various  directions  and  at  the  confluence  or 
sulci,  the  enamel  is  not  usually  perfect  which  makes  the  crown  prone 
to  decay  at  these  points. 

The  neck  is  square  in  outline,  much  depresvsed  on  the  buccal  and 
labial  side,  near  the  place  where  the  root  divides.  The  anterior  margin 
of  the  neck  is  slightly  concave,  where  the  root  begins  to  flatten  on  its 
surface.  The  posterior  margin  of  the  neck  is  usually  convex,  matching 
the  posterior  face  of  the  root  which  seldom  bifurcates. 


THE   TKETII  115 

The  roots  arc  two  in  iuinil)er,  usuall>'  well  se[jaratcd  near  their 
points.  The  anterior  root  is  quite  flattened  and  concave  transversely, 
it  is  more  inclined  to  bifurcate  than  the  posterior  nKjt;  the  i)uli)  of  the 
bifurcated  root  sei)arates  into  two  di\isions,  one  in  each  root  canal, 
niakini;  this  root  difficult  to  treat. 

Ihic  mandibular  second  molar  is  situated  between  the  first  and 
third  molar;  it  articulates  with  the  posterior  i)orlion  of  the  morsal 
face  of  the  lirsl  nuixillary  molar  and  the  anterior  pt^rtion  of  the  morsal 
face  of  the  second  maxillary  molar. 

The  crown  is  nearer  a  cube  than  the  hrst  and  third  molars,  i.  e., 
is  nearly  of  the  same  length  and  breadth  and  has  five  faces:  buccal, 
palatal,  anterior,  posterior,  and  morsal. 

The  buccal  face  is  usually  convex  in  both  directions.  On  its  upper 
morsal  edge  it  is  divided  into  two  portions,  helping  to  form  the  anterior, 
canine,  and  posterior,  molar  cusps.  Sometimes  at  the  base  of  this 
division  a  fissure  commences  and  passes  down  the  centre  of  this  face 
to  a  pit,  this  induces  decay  of  this  part.  The  upper  half  of  this 
face  inclines  inward,  allowing  the  buccal  cusps  of  the  first  and  second 
maxillary  molars  to  overlap  the  crown. 

The  lingual  face  is  rounded  or  convex  in  all  directions.  On  its 
morsal  edge  it  is  divided  into  two  lingual  faces,  the  anterior  and  pos- 
terior cusps;  on  its  lower  margin  it  is  concave  near  the  commencement 
of  bifurcation  of  the  two  roots. 

The  anterior  and  posterior  faces  are  similar  to  those  of  the  first 
molar,  the  anterior  being  somewhat  convex  in  the  upper  portion  and 
concave  in  the  lower;  the  posterior  face  is  more  convex  than  the 
anterior. 

The  morsal  face  is  usually  divided  into  four  cusps;  occasionally 
there  is  a  cingulum  giving  it  five  cusps.  At  the  base  or  confluence  of 
these  cusps  there  are  irregular  fissures  or  sulci,  the  enamel  not  being 
well  formed  or  joined  together  at  these  points  makes  them  prone  to 
decay. 

The  neck  in  cross-section  is  a  square  in  outline  with  concave  depres- 
sions on  the  sides. 


116  THE  MOUTH 

The  roots  are  two  in  number,  flattened  anteriorally  and  posterior- 
ally  with  a  strong  inclination  to  bifurcate. 

The  pulp  chamber  and  pulp  canal  is  a  miniature  of  the  crown  and 
roots;  there  are  usualh^  two  pulp  canals  in  the  anterior  root  and  one 
in  the  posterior,  though  in  many  cases  there  are  two.  The  number 
of  pulp  divisions  being  governed  by  the  number  of  bifurcations  of 
the  roots. 

The  third  mandibular  molar  is  usually  of  the  same  general  char- 
acter as  the  first  or  second  molar,  though  like  the  third  maxillary 
molar  it  is  subject  to  great  variations,  as  to  the  number  of  cusps,  roots, 
and  pulp  canals. 

The  crown  has  five  faces  as  in  the  first  molar,  and  usually  the  same 
number  of  cusps.  The  posterior  face  differs  from  that  of  the  first  and 
second  molar  in  being  more  convex  or  rounded  in  order  to  make  a 
"finishing  tooth." 

The  morsal  face  is  similar  to  that  of  the  first  molar,  though  it  is 
more  liable  to  vary  from  the  typical. 

The  neck  of  the  tooth  is  about  the  same  as  the  first  molar,  subject 
to  great  variations  as  to  the  number  of  roots  and  their  positions,  they 
may  be  compressed  together,  spread  apart,  or  curved  abruptly  back- 
ward. 

The  roots  vary  in  number,  sometimes  there  is  apparently-  only  one 
root,  but  a  cross-section  w411  show  several  roots  compressed  together, 
each  with  its  separate  pulp  canal;  occasionally  two  roots  are  found 
well  separated  near  the  neck,  allowing  an  isthmus  of  bone  to  pass 
Ijetween  them,  with  the  roots  finally  uniting  farther  down  (see  Figs. 
123  and  124).  This  condition  makes  the  tooth  very  diflicult  to 
extract.  Occasionally  the  crown  and  roots  form  the  segment  of  a 
circle  (see  Fig.  123). 

The  roots  of  the  third  molar  sometimes  grow  down  and  backward, 
passing  beyond  the  mandibular  canal  (see  Fig.  338). 

The  following  interesting  observation  is  given  by  Dr.  Hermann 
Prinz: 

"Certain  anatomical  malformations  of  the  roots  of  the  lower  third 
molars  may,  on  rare  occasions,  be  the  cause  of  very  profuse  hemor- 


rilE  TEETH  117 

rhage,  and  other  serious  damaiic  as  a  result  ol  their  extraction.  Tliere 
are,  as  far  as  the  authoi-  knows,  li\e  cases  on  record  in  which  the 
developing  tooth  inclosed  in  the  body  of  its  roots  the  contents  of  the 
mandibular  canal — their  artery,  vein,  and  nerve  (sec  F'igs.  123  and  124). 
The  extraction  of  a  tooth  j^ossessing  such  malformations  means  tearing 
of  the  \essels  and  the  ner\  e,  causing  extreme  henKjrrhage,  excruciating 
pain,  and  linalh'  i)ermanent  insensibilit\-  of  one-half  of  the  lip.  These 
are  the  s>-mi)toms  as  recorded  fnjm  cases  which  occurred  in  the 
practices  of  Roese,  of  Munich,  in  11X98,  and  of  X'orslund-Kjaer,  of 
Copenhagen,  in  1908." 

Deciduous  Teeth. — The  twenty  deciduous  teeth  are  much  smaller 
than  the  permanent  ones.  In  infancy  they  fill  the  jaws,  otten  over- 
lai)ping  each  other,  until  the  last  one  is  in  i)lace.  As  the  jaws  grow  and 
exi)and  continuoush'  from  their  first  de\eloi)ment,  the  deciduous  teeth, 
b\-  the  time  the  child  is  five  years  of  age,  instead  of  overlai:)ping  are 
often  quite  separated  from  each  other,  as  the>'  do  not  increase  in  size 
after  they  are  once  formed. 

The  twelve  anterior  deciduous  teeth  are  similar  in  character  to  the 
l)ermanent  ones,  though  very  much  smaller. 

The  eight  deciduous  molars  are  similar  to  the  permanent  molars, 
though  very  much  smaller,  their  roots  diverge  much  more  in  order 
to  give  room  for  the  development  and  growth  of  the  premolar  teeth. 
In  examination  of  .v-rays  (Fig.  120)  the  relative  position  of  the  pre- 
molars to  the  deciduous  molars  is  well  illustrated.  The  roots  of  the 
deciduous  teeth  become  resorbed  and  the  i)ermanent  teeth  advance 
into  their  normal  positions.  The  position  of  the  i)remolar  should  be 
remembered  when  extracting  a  deciduous  molar;  the  forceps  must 
not  be  placed  too  far  upon  the  tooth  as  there  is  danger  of  displacing 
the  premolar.  Should  the  roots  of  the  deciduous  tooth  break  during 
extraction  it  will  do  no  harm,  as  they  are  quickly  resorbed. 

Fig.  107  is  taken  from  the  skull  of  a  child  of  alx)ut  six  >ears,  show- 
ing all  the  deciduous  teeth  in  position  and  the  developing  permanent 
teeth,  except  the  third  mandibular  molar  and  the  second  and  third 
maxillar\-  molars,  which  at  this  period  of  life  are  of  very  immature 
devel()])ment.      The    outer    i)lates   of    the    aheolar    jirocess     and     the 


118  THE  MOUTH 

cancellated  tissue  ha^'e  been  removed,  in  order  that  the  positions  and 
relations  of  the  dental  organs  at  this  period  of  life  may  be  more 
clearly  seen. 


Fig.  107. — Skull  of  a  child,  aged  about  six  years,  showing  all  the  deciduous  teeth  in  position  and 

the  developing  permanent  ones. 


ERUPTION  OF  TEETH. 

The  deciduous  teeth  usually  commence  eruption,  according  to  C.  S. 
Tomes,  as  follows: 

Mandibular  first  incisors,  from  six  to  nine  months. 

Maxilla  or  upper  first  incisors,  from  eight  to  ten  months. 

Mandibular  second  incisors  and  first  molars,  from  fifteen  to  twenty- 
one  months. 

Canines,  from  sixteen  to  twenty  months. 

Second  molars,  from  twenty  to  twenty-four  months. 

By  close  observation  it  will  be  found  that  the  above  table  is  liable 
to  considerable  variation. 


ERi'PTIOX  or   TEETH  119 

According  to  Holt :' 

At  the  age  of  one  \ear  a  cliild  should  ha\e  six  teeth. 

At  the  age  of  one  and  a  half  \ears  a  child  should  have  twelve  teeth. 

At  the  age  of  two  years  a  child  should  have  sixteen  teeth. 

At  two  and  a  half  years  a  child  should  ha\e  twent>-  teeth. 

X'arious  authorities  give  eruption  of  the  permanent  teeth  as  follows: 

The  mandibular  teeth  precede  those  of  the  maxilla  by  short  intervals. 

First  molars,  sixth  year. 

First  central  incisors,  seventh  \ear. 

Two  second  lateral  incisors,  eighth  \ear. 

First  premolars,  ninth  \ear. 

Second  premolars,  tenth  year. 

Canines,  eleventh  to  twelfth  >ear. 

Second  molars,  twelfth  to  thirteenth  year. 

Third  molars,  se\enteenth  to  twenty-fifth  year.= 

The  deciduous  teeth  commence  to  be  shed  about  the  age  of  six, 
beginning  usually  with  the  mandibular  first  incisors,  soon  followed  by 
the  first  maxillary  incisors.  The  permanent  first  incisors  soon  taking 
their  places.  These  teeth  will  often  overlap  each  other.  Then  the 
second  incisors  are  shed  and  the  permanent  ones  fill  their  places. 
In  many  children's  mouths  these  teeth  do  not  erupt  into  their 
typical  positions,  sometimes  from  lack  of  room,  but  more  often 
because  the  deciduous  teeth  are  either  not  shed  at  the  proper  time, 
or  they  are  lost  too  early,  either  b>-  deca\-,  accident  or  injudicious 
extraction. 

The  time  of  shedding  the  canine  teeth  is  less  definite  than  that  of 
the  other  deciduous  teeth.  If  they  can  be  held  in  position  until  the 
premolars  have  erupted  there  will  be  a  better  space  reserved  for  the 
permanent  canines  to  erupt. 

The  deciduous  first  molars  are  usualh'  shed  the  eighth  year  and 
the  second  molars  at  nine  years  of  age.  These  deciduous  molar  teeth 
are  not  replaced  by  molar  teeth,  but  b\-  the  premolars. 

1  Gray's  Anatomy,  eighteenth  edition,  p.  1125. 

-  The  foregoing  table  is  from  Gray's  .Anatomy,  eighteenth  edition,  p.  1125. 


120  THE  MOUTH 

From  about  the  age  of  five  or  six  years,  before  any  of  the  deciduous 
teeth  are  shed,  there  are  more  fully  developed  teeth  and  those  in  pro- 
cess of  growth  in  the  mouth  than  at  any  other  period  of  life,  at  least 
forty-eight  teeth  are  in  various  stages  of  transition.  The  roots  of  the 
deciduous  teeth,  twenty  in  number,  are  becoming  resorbed  and  pre- 
paring to  be  shed,  while  the  roots  of  many  of  the  permanent  teeth  are 
developing,  also  the  roots  and  crowns  of  later  permanent  teeth  are 
growing  and  changing  their  positions  in  the  jaws.  This  great  activity 
goes  on  from  day  to  day  without  any  pathological  disturbance  in  nor- 
mally developed,  healthy  children,  but  any  disturbance  which  would 
cut  off  the  nourishment  or  interfere  with  the  circulation  of  the  jaws 
proper,  as  w^ell  as  of  the  teeth,  might  bring  about  pathological  condi- 
tions that  would  not  only  affect  the  parts  locally  but  by  reflex  action, 
cause  systemic  troubles  such  as  chronic  migraine,  indigestion,  disturb- 
ances of  the  brain  centres  inducing  corea,  epilepsy,  neurasthenia,  and 
other  diseases  of  this  character.  This  matter  w^ill  be  further  spoken 
of  under  Impacted  Teeth  (see  page  i66).  An  abnormal  deposit  of  salts 
of  calcium  may  occur  in  the  bone,  which  may  prevent  the  teeth  from 
erupting  into  their  normal  positions,  or  might  even  cause  the  can- 
cellated tissue  of  the  alveolar  process  to  become  fixed,  producing  a 
narrow,  dental  arch,  which,  in  turn,  forces  the  tongue  back  into  the 
pharynx,  carrying  the  soft  palate  upward  and  plugging  the  posterior 
nares,  thus  interfering  with  respiration  through  the  nasal  passage 
and  blocking  the  proper  drainage  of  the  nasal  cavity  and  its  accessory 
sinuses.  One  has  only  to  look  at  Figs.  113  and  114  to  see  the  mass 
of  tooth  organs  and  to  realize  the  mischief  which  could  be  produced 
by  injudicious  mechanical  interference  at  this  time,  as  well  as  by 
pathological  disturbances. 


VARIOUS   ILLUSTRATIONS   OF  JAWS  AND   TEETH. 

Fig.  108.  The  anterior  portion  of  the  base  of  a  typical  skull,  show- 
ing the  bones  forming  the  roof  of  the  mouth,  the  sutures,  and  the 
various   foramina.      The   occluding   surfaces   of   the   sixteen   maxillary 


ERLiTiox  or  ri-.ivni 


121 


teeth  ha\  o  an  outward  inclination,  while  the  nianclil)ular  teeth  are 
inchned  inward.  1  his  allows  the  outer  cusjjs  of  the  U])i)er  teeth  to 
"bite"  over  the  (juter  iusi)s  ol  the  lower  teeth  (see  Fig.  iii).  The 
zyp:oniatic  arches  extend  from  the  zxiioma  at  the  side  of  the  upper  jaw 


Fig.  108. — .interior  portion  of  the  base  of  a  typical  skull. 

to  the  temporal  bone,  thus  giving  the  support  of  a  flying  buttress  to 
the  maxillae.  The  i^osterior  nares  can  be  seen  separated  b>'  the  \'omer, 
which  also  assists  in  supporting  the  upper  jaw. 

Fig.  109.     Upper  portion  of  the  body  of  a  topical  mandible,  show- 
ing the  occluding  surfaces  of  the  sixteen  mandibular  teeth,  which  are 


122 


THE  MOUTH 


ill  good  alignment ;  the  outer  faces  of  the  buccal  cusps  have  an  inward 
inclination  which  allows  the  buccal  cusps  of  the  maxillary  teeth  to 
occlude  o\'er  them. 

Fig.  1 10^  gives  an  anterolateral  view  of  an  almost  ideal  occlusion 
of  the  permanent  teeth.  The  illustration  shows  the  relation  of  the 
bones  forming  the  external  structures  of  the  jaws.  The  outer  surfaces 
of  the  lateral  and  anterior  walls  of  the  maxillary  sinus  are  shown,  the 


Fig.  109. — Upper  part  of  the  body  of  a  typical  mandible. 

teeth  having  been  denuded  of  the  external  plate  of  the  alveolar  process. 
It  will  be  seen  that  in  removing  the  external  plate  the  maxillary  sinus 
has  been  opened  into  immediately  over  the  roots  of  the  molars,  showing 
how  thin,  in  this  case,  is  the  bone  between  the  roots  of  the  teeth  and 
the  external  wall  of  the  sinus.  It  is  also  very  thin  over  the  roots  of  the 
canine  and  first  and  second  premolars. 

Figs.  43,  44  and   no  demonstrate  the  arrangement  of  the  cancel- 

'  Fig.  110  is  a  duplication  of  Fig.  31. 


KRLPT/OX  OF  TEETH 


123 


lated  tissue  Iji'twccn  the  icclh,  also  iK'twccn  llu-  tct-lh  and  llu-  cortical 
l)()iu',  where  il  acts  as  an  clastic  cushion  to  lessen  shock  fnjni  blows 
upon  the  mandible  or  from  concussi(;n  in  mastication,  it  is  this  arrange- 
ment which  jjermits  the  movement  of  the  teeth  in  \arious  directions 
diu'ing  eruption  or  in  correcting  irregularities  of  the  teeth. 


Fig.  110. — Anterolateral  view  of  the  maxilla  and  mandible  with  the  external  plates  of  the  alveolar 
process  and  some  of  the  cancellated  tissue  removed,  exposing  the  roots  of  the  teeth,  the  cribriform 
tubes,  and  mandibular  canal. 


Fig.  III.  The  right  side  of  the  lower  portion  of  the  face,  showing 
the  relation  of  the  mandible  with  the  base  of  the  skull.  It  also  shows 
a  typical  occlusion  of  the  teeth,  each  tooth  occluding  with  two  other 
teeth,  excei^t  the  third  maxillary  molar  and  the  first  mandibular 
incisor. 


124 


THE  MOUTH 


Fig.  112.  A'-ra>-  of  the  lower  portion  of  the  right  maxilla  and  the 
mandible,  showing  the  internal  structures,  such  as  the  cancellated  tissue, 
the  shapes  of  the  roots,  and  their  relation  w^ith  surrounding  tissue.  The 
mandibular  canal,  the  maxillary  sinus  and  a  portion  of  the  mastoid 
cells  are  outlined.  The  occlusion  of  the  teeth  is  good.  A  rudimentary 
maxillar^'  fourth  molar  is  also  shown. 


Fig.  111. — The  right  side  of  the  lower  portion  of  face. 

Fig.  113,  an  .v-ray  from  a  living  subject,  showing  maxillary  and 
mandibular  teeth.  The  first  mandibular  molar  has  been  diseased, 
treated,  and  filled.  The  anterior  root  is  flattened  and  not  of  easy 
access,  consequently  the  canal  has  not  been  properly  filled,  the  pos- 
terior root  is  larger  and  nearer  straight,  so  treatment  is  not  difificult, 
shown  by  the  better  filled  root.  The  roots  of  the  second  mandibular 
molar  are  compressed,  probably  owing  to  lack  of  room  at  the  time  of 
formation,  the  si)ace  being  small  between  the  first  molar  and  the 
morsal   face  of  the  third   imi)acted  molar.     The  third  molar  is  of  the 


ERirriox  Oh'  ruETii 


12.") 


usual  (>!)(.'  of  iuipaclion  al\va\s  diHicult  (o  extract,  its  uiorsal  lace  is 
not  ()iil\  interlocked  with  the  second  molar  tooth,  hut  its  j)eculiar- 
shaped  roots  are  imbedded  uixler  hard,  c(trlical  l)one.  As  soon  as 
such  impaction  is  discoxered,  one  \v(mld  be  justified  in  extracting  the 
second  molar,  allowin.u  the  third  to  remain  for  future  development. 


Vie.  112. — A'-ray  of  dried  skull.     (A'-ray  1)\-  Dr.  Pancoast.) 

The  first,  second  and  third  maxillary  molars  arc  all  abnormal; 
their  roots  are  compressed;  the  third  molar  is  impacted  against  the 
lX)sterior  ]:)()rtion  of  the  second  molar.  In  this  case  also  the  second 
molar  should  be  extracted  first  as  there  would  be  great  lial)ilit>'  of 
damaging  the  tissue  surrounding  the  third  molar.     A  portion  of  the 


120  THE  MOUTH 

root  is  above  the  floor  of  the  maxillary  sinus.  The  second  molar  with 
its  compressed  roots  often  gives  serious  trouble  through  the  pulp 
becoming  diseased. 


Fk,.  U.S. — A'-ray  of  living  sul)ject.      (A'-ray  by  Dr.  Pancoast.j 

Fig.  114.     Horizontal  section  made  at  the  necks  of  fourteen  man- 
dibular teeth,  showing  the  shape  of  the  teeth  in  cross-section  at  this 


ERUPTION  OF  TEETH 


127 


point,  also  the  shape  and  size  of  the  pulj)  chambers  in  a  matured  skull. 
In  a  younger  skull  llu'  pulj)  chamber  would  be  relati\el\-  larger. 


Fig.  114. — Horizontal  section  made  at  the  necks  of  fourteen  mandibular  teeth. 


Fig.  115. — Horizontal  section  made  at  the  necks  of  sixteen  mandibular  teeth. 

Fig.  115.     Horizontal  section  made  at  the  necks  of  sixteen  mandib- 
ular teeth,  showing  the  shape  and  relation  of  the  teeth  at  this  point. 


128 


THE  MOUTH 


It  also  shows  the  investing  membranes  of  the  teeth  and  the  hning  of 
the  sockets.  The  periodontal  membrane  has  various  functions,  it 
acts  as  a  cushion  between  the  tooth  and  the  bone,  and  assists  in  hold- 


/, 


\  r 


Fig.  116. — Anteroposterior  section  through  the  maxillary  sinus,  alveolar  process  and  the  teeth. 


Fig.  117. — •A'-ray  picture  of  the  left  half  of  the  lower  portion  of  an  upper  jaw. 
(JV-ray  by  Dr.  Pancoast.) 


K/urriox  OF  ri:i:rii 


12!  > 


ini;  the  tooth  in  the  alveohis,  Rixini;  njoni  for  the-  passage  of  nutrient 
vessels  and  ncrx'es. 

Fiu,.    I  If).      Anter()i)()sterior    section    through    llic   maxillary    sinus, 
aheolar  process  and  the  teeth,  showing  the  relation  of  the  teeth  to  each 


Fig.  118. — ,Y-ray  picture  of  the  right  half  of  the  lower  portion  of  an  upper  jaw. 
(A'-ray  by  Dr.  Pancoast.) 


Fig.  119. — X-ray  of  the  right  half  of  the  body  of  the  mandible.     (X-ray  by  Dr.  Pancoast.) 

other  and  to  the  maxillary  sinus,  which,  in  this  particular  skull,  are 

normal  though  not  typical.     The  shapes  of  the  pulp  cavities  are  also 

indicated. 

Figs.  117  and  118.     Two  .v-ray  i)ictures  of  the  right  and  left  halves 

of  the  lower  portion  of  an  upper  jaw.     This  skull   is  nearer   typical 
9 


130 


THE  MOUTH 


Fig.  120 


Fig.  121 
Figs.  120  and  121. — Z-ray  pictures  of  the  left  half  of  the  maxilla  and  mandible  of  a  child,  about 
five  years  of  age,  showing  ten  deciduous  and  twelve  permanent  teeth;  the  latter  are  in  the  process 
of  formation.     (X-rays  by  Dr.  Pancoast.J 


ERLJ'TIOX  OF    TEETH 


131 


than  that  in  Fig.  ii6.  Tlic  hnvcr  (juthncs  of  the  niaxiUar)-  sinuses  are 
shown,  also  the  alveolar  i)rocesses,  the  pulp  cavities,  and  their  canals. 
The  api)arent  relations  of  the  roots  of  the  teeth  to  the  maxillar>-  sinuses 


# 


// 


\f^ 


-  f 


K 


-V  NOP 

Fig.    122. — Si.xteen  teeth  taken   from  one  skull;   nearly  all  of  the  roots    have  some   peculiarity 

(Through  courtesy  of  Dr.  Ottolengui.) 


132 


THE  MOUTH 


f*u*. 


( .-• 


L* 


v 


.    / 


E 


|»^-   \ 


V. 


M 


^ 


^ 


A^ 


D 


H 


^  9 


QB 


Q  R  ST 

Fig.  123. — A  collection  of  twenty  abnormal  teeth;  among  them  are  fusions,  odontomes, 

and  irregularities,  etc. 


ERUPTIOX  OF  TEETH 


133 


are  clecei)ti\c'  to  one  not  familiar  willi  .v-ra\   i)i(tiires.     Tlie  lower  out- 
lines of  the  sinuses  are  l)elo\v  the  jxiints  ot  the  roots  (;1  tlie  teeth,  which 


p  q  r 

F"lG.  12-4. — ^A  group  of  nineteen  abnormal  teeth. 


might  indicate  that  the  ends  of  the  roots  had  penetrated  the  sinus, 
instead  of  this  they  are  in  the  walls  of  the  sinus  (see  Fig.  97).     The 


134  '  THE  MOUTH 

white  lines  running  downward  and  forward  from  the  posterior  wall 
of  the  sinuses  are  the  grooves  or  canals  for  the  passage  of  the  maxillary 
nerves  and  vessels;  branches  may  be  seen  going  to  roots  of  the  various 
teeth. 

Fig.  119.  X-ray  of  the  right  half  of  the  body  of  the  mandible,  show- 
ing the  cancellated  tissue  of  the  bone,  a  typical  view  of  the  teeth,  and 
outlines  of  the  pulp  chambers  and  canals. 

Figs.  120  and  121.  X-ray  picture  of  the  left  half  of  the  maxilla  and 
mandible  of  a  child,  about  five  years  of  age,  showing  ten  deciduous 
and  twelve  permanent  teeth;  the  latter  are  in  the  process  of  formation. 

Fig.  122.  Sixteen  teeth  taken  from  one  skull.  It  will  be  noticed 
that  nearly  all  of  the  roots  have  some  peculiarity.  A,  right  mandibular 
third  molar,  four  roots;  the  anterior  and  posterior  are  flattened  with 
two  apical  foramen  in  each  root.  A  buccal  root  is  well  shown,  and 
there  is  also  a  small  lingual  root  not  shown,  making  six  apical  foramina; 
C  and  D,  right  first  and  second  maxillary  premolars,  two  roots  each; 
£,  left  maxillary  third  molar,  five  roots;  F,  left  mandibular  second 
molar,  the  anterior  and  posterior  roots  both  bifurcated;  G,  left  man- 
dibular second  premolar,  three  roots;  H,  left  mandibular  first  premolar, 
two  roots;  K,  right  maxillary  second  premolar,  three  roots;  L,  left 
maxillary  first  premolar,  two  roots;  M,  left  mandibular  third  molar, 
three  roots;  0,  left  mandibular  second  premolar,  three  roots;  P,  right 
mandibular  first  premolar,  three  roots  compressed  together. 


THE  VASCULAR  SUPPLY  OF  THE  TEETH. 

The  teeth  receive  their  supply  from  the  internal  maxillary  artery, 
which  also  supplies  all  the  deep  portions  of  the  face,  including  part 
of  the  floor  of  the  mouth,  the  palate,  the  nasal  cavities,  the  maxillary 
sinus,  the  greater  portion  of  the  ethmoid  cells,  part  of  the  pharynx, 
and  part  of  the  dura  mater  of  the  brain. 

The  supply  to  the  maxillary  teeth  comes  from  the  internal  maxil- 
lary, through  the  alveolar  artery.  It  passes  through  the  foramen, 
just  along  the  tuberosity  of  the  maxilla  into  the  sinus,  passing  forward 


THE   VASCULAR  SIPPLV  OF   THE  TEETH  135 

on  the  outer  wall  of  the  sinus  and  entering  the  anterior  wall  where 
it  anastomoses  freelx'  with  the  iiifraorhital  and  other  arteries.  During 
its  course  it  gives  ofY  branches  t(j  the  roots  of  the  nia\illar\-  teeth,  their 
investing  meml^rane.  the  alve(jlar  process,  and  the  mucous  memljrane 
of  the  maxillar\-  sinus.  In  a  general  way  it  accomi)anies  the  superior 
alveolar  ner\e. 

The  hrst  or  maxillar\'  division  of  the  internal  maxillary  arter>' 
extends  from  the  external  carotid  to  the  sphenomandibular  ligament, 
and  gives  off  fi\e  branches,  which  ])ass  into  or  through  osse(jus  fora- 
mina. These  branches  are  the  deej)  auricular,  anterior  tympanic, 
middle  and  small  meningeal,  and  the  inferior  alveolar. 

The  second  or  pter}goid  division  extends  from  the  sphenoman- 
dibular ligament  to  the  point  at  which  the  artery  passes  through  the 
space  between  the  two  heads  of  the  pterygoideus  externus  (external 
pter>'goid  muscle).  This  portion  has  six  branches  which  supph'  the 
masticatory  and  buccinator  muscle.  They  are  named,  according  to 
their  distribution,  the  two  deep  temporal,  two  pterygoid,  the  masse- 
teric, and  the  buccinator. 

The  third  or  pterygopalatine  division  extends  from  the  inner  surface 
of  the  internal  pterygoid  muscle  to  the  termination  of  the  artery  in 
the  pterygopalatine  fossa.  It  gives  off  six  branches,  each  passing  into 
or  through  the  osseous  foramina.  They  are  likewise  named  according 
to  the  parts  supplied  by  them,  the  alveolar  already  described,  infra- 
orbital, descending  palatine,  artery  of  the  pterygoid  canal,  pharyngeal, 
and  sphenopalatine. 

The  inferior  alveolar  artery  arises  from  the  under  part  of  the  internal 
maxillar\-.  It  passes  downward  and  forward  between  the  sphenoman- 
dibular ligament  and  the  neck  of  the  mandible  to  the  mandibular 
foramen,  through  which  it  passes  into  the  canal,  accompanied  by 
the  alveolar  nerve,  it  then  terminates  anterior  to  the  mental  foramen, 
where  it  separates  into  two  divisions,  known  as  the  incisor  and  mental 
branches. 

The  m\  loh\oid  branch  is  given  off  from  the  inferior  alveolar  arter>' 
immediately  before  entering  the  foramen.  It  descends  into  the  mylb- 
h\-oid  groove  with   the  nerve  and  \'essels  of  the  same  name,  and  is 


136  THE  MOUTH 

distributed  to  the  under  surface  of  the  mylohyoid  muscle.  The  por- 
tion of  the  alveolar  artery  within  the  canal  gives  off  numerous  small 
branches  to  supply  the  teeth  and  their  surroundings.  The  incisor 
branch  is  a  continuation  and  passes  forward  within  the  cancellated 
structure  of  the  bone  to  supply  the  region  of  the  chin  and  the  anterior 
teeth. 

The  mental  branch  passes  through  the  mental  foramen,  accom- 
panied by  the  nerve  of  the  same  name,  and  supplies  the  soft  parts  in 
the  region  of  the  chin. 

In  this  manner  the  mandible  is  richly  supplied  with  blood. 

As  the  inferior  alveolar  artery  enters  the  bone  at  the  mandibular 
foramen,  it  passes  downward  and  forward  through  the  body  of  the 
bone  to  the  symphysis,  and  anastomoses  with  the  artery  from  the 
opposite  side.  At  a  point  near  the  incisor  teeth  a  great  portion  of  the 
artery  curves  upon  itself  and  passes  out  through  the  mental  foramen, 
anastomosing  with  the  submental,  inferior  and  superior  labial  or 
coronary  branches  of  the  external  maxillary  or  facial  artery.  In  this 
manner  two  complete  collateral  circulations  are  formed  on  the  two 
sides.  The  mandible  is  also  well  supplied  through  the  periosteum  of 
the  body  of  true  bone  and  the  mucoperiosteum  of  the  alveolar  pro- 
cess. The  vessels  from  these  sources  pass  into  the  bone  and  have 
free  anastomotic  relations  with  the  internal  supply  of  blood. 

Fig.  125  is  from  an  .x-ray  picture  of  the  left  half  of  a  mandible  of  a 
mature  dog,  which  was  injected  through  the  inferior  alveolar  artery. 
The  illustration  shows  that  the  mercury  passed  through  the  artery 
to  all  portions  of  the  bone,  the  alveolar  process,  and  the  teeth,  and 
demonstrates  the  complete  anastomotic  relations  which  the  arteries 
have  to  each  other.  A  stereoscopic  picture  would  show  that  branches 
are  given  off  from  the  artery  as  it  passes  along  its  canal  or  tube,  to 
the  roots  of  the  teeth  and  the  intervening  tissue.  It  proves  that  any 
portion  of  the  artery  can  be  removed  without  destroying  the  vitality 
of  any  tissue  of  the  jaw,  provided  that  the  artery  be  not  destroyed 
between  the  structures  and  the  nearest  branch  of  the  collateral  circu- 
lation, and  also  shows  that  in  order  to  destroy  the  vitality  of  a  tooth 
pulp  the  blood  supply  would  have  to  be  cut  off  immediately  at  the 
apical  foramen. 


THE   VASCLLAR  SIPPLV  OF  THE  TEETH 


137 


It  tloc's  not  follow  that  a  tooth  that  docs  not  "respond"  to  tliciinal 
changes,  or  vwn  to  the  electric  cnrrent,  is  necessarily  a  (le\itali/A'd 
tooth,  in  operations  for  neiirali;ia  the  surgeon  often  removes  a  great 
portion  of  the  mandibular  vessels  and  nerve,  or  he  may  remove  the 
semilunar  ganglion,  hut  in  so  doing  he  does  not  destroy  the  vitality  of 
the  tissue  supi)lied.  He  destroys  the  function  of  communication  with 
the  sensoriuni.  When  the  trigeminal  nerve  is  crii)pled  by  resection  or 
b>'  the  remoxal  of  the  semilimar  ganglion,  the  wise  surgeon  protects 


Fig.  125. — From  an  jc-ray  picture  of  the  mandible  of  a  dog.     The  arteries  had  been  injected  with 

mercury.     (X-ray  by  Dr.  I^ancoast.) 

the  parts  from  injury.  A  tooth  under  similar  conditions  should  also 
be  protected  and  not  subjected  to  "test."  In  time  it  will  regain  its 
sensation,  provided  meddlesome  surgery  has  not  destroyed  the  pulp. 

In  the  application  of  a  spray  of  ethyl  chlorid  to  the  gums  to  produce 
an  anesthetic  condition  for  lancing  an  abscess,  great  care  should  be 
taken  to  protect  any  vital  tooth,  for  there  may  be  danger  of  pro- 
ducing its  devitalization  by  the  sudden  and  extreme  lowering  of  its 
temperature. 


138 


THE  MOUTH 


Incifor  hranch 


Fig.  126.— The  internal  maxillary  artery.      (Gray.) 


pharyngeal 


SjjhenojJcdatine 
raqrbital 


Post.  SU2).  alveolar 


I  Mylohyoid 
Fig.  127. — Plan  of  branches  of  internal  maxillary  artery.     (Gray.) 


SEXSORV  XEKVE  SUPPLY  OF   TEETH  AM)  FACE  i:',!) 


THE    SENSORY    NERVE    SUPPLY    OF    THE    TEETH   AND    FACE. 

The  Trigeminal  Nerve. — The  sensory  ner\e  siii)j)ly  ol  the  teeth 
and  associated  i)arts  is  governed  by  the  trigeminal  (trifacial  or  fifth 
ner\e),  w  liich  is  the  largest  of  all  the  cranial  ner\es.  Through  its  wide 
distribution  within  the  face  and  head,  its  close  relation  to  other  nerves 
and  to  the  ])lexuses  and  ganglia  of  the  sympathetic  s>stem  (Fig.  128), 
it  becomes  inxohed  in  nearly  all  the  diseases  of  the  external  portion 
of  the  head  as  well  as  the  superficial  and  deep  j)arts  of  the  face.  "The 
intimate  relations  which  the  nerve  bears  with  the  points  of  origin  of 
the  sixth,  seventh,  eighth,  ninth,  tenth,  ele\enth,  and  twelfth  cranial 
ner\es  in  the  floor  of  the  fourth  ventricle  jiossibly  explain  many  of 
those  phenomena  which  are  considered  as  reflex  in  character,  and  whose 
starting-point  seems  to  depend  upon  some  irritation  of  the  fifth  nerve 
by  means  of  various  branches"  (Ranney).  It  resembles  a  spinal  nerve, 
in  that  it  arises  by  two  roots,  anterior  and  posterior.  The  posterior 
root  is  sensor}'  in  character,  and  has  a  ganglion  upon  it,  while  the 
anterior  root  has  no  ganglion  and  is  motor  in  character. 

The  large,  sensor\',  or  posterior  root  emerges  from  a  point  in  close 
proximity  to  the  centre  of  the  lateral  surface  of  the  i)ons  \'arolii,  but 
nearer  its  superior  than  its  inferior  border. 

The  small,  motor,  or  anterior  root  is  made  up  of  six  or  eight  rounded 
filaments  (Vulpian),  and  emerges  from  the  jjons  a  little  above  the  larger 
posterior  root,  being  separated  from  it  b\-  a  few  transverse  fibers  of 
white  substance.  It  is  entirely  distinct  and  separate  from  the  larger 
sensory  root  until  it  passes  out  of  the  cranial  cavit>-  through  the  foramen 
ovale,  when  it  becomes  closeh'  united  with  the  third  or  mandibular 
division. 

The  deep  origin  of  these  two  roots  is  widely'  separated  from  their 
superficial  origin.  Following  them  backward  from  the  anterior  surface 
of  the  pons  Varolii,  they  pass  directly  through  the  pons  to  the  medulla 
oblongata,  without  an>-  connection  whatever  with  its  fibers.  On  reach- 
ing the  medulla  the\'  form  three  main  dixisions,  one  anterior  and  two 
posterior. 


140 


THE  MOUTH 


J  Facial  nerve 

Communicates  between  facial  and 
,  .   tympanic  nerves 

.  Nervus  intermedius  {of  Wrisberg) 

^  -Genicular  ganglion 

_  ,  Greater  superficial  petrosal  nerve 

Commu7iicates  between  great  superficial 
petrosal  and  tympanic  nerves 

-  -  Small  superficial  petrosal  nerve 

Internal  carotid  plexus 
J  .  Deep  petrosal  nerve 

Nerve  of  pterygoid  canal 


■<"^.- Trigeminal  nerve, 
sensory  root 
/•k"^^-  Trigeminal  nerve, 
\  motor  root 

Mandibular  nerve 


■A'-T 


Ophthalmic  nerve 
"  Maxillary  nerve 

'  Optic  nerve 

^    Infra-orbital  nerve  with  zygo- 
maticotemporal nerve 

Branch  of  infra-orbital  nerve 
Zygomaticotemporal  nerve 


SENSORY  NERVE  SiPPLV  OF   TEETH   AM)  FACE  141 

The  anterior  or  motor  division  arises  from  the  motor  luirlcus  (A 
the  trigeminal  ner\e.  which  is  comijosed  of  hirge,  ramihed,  and  i)ig- 
mented  cells  situated  below  the  lateral  angle  of  the  fourth  ventricle, 
anterior  to  the  inferior  facial  nucleus,  and  on  the  proximal  side  of  the 
large  sensory  nucleus  of  this  nerve.  It  also  arises  from  the  gray  matter 
at  the  anterior  portion  of  the  iter  beneath  the  corpora  quadrigemina. 

77/c  two  posterior  or  sensory  divisions  gi\e  general  sensibilit\-  to 
the  face  and  head,  extending  as  far  back  as  its  vertex. 

From  their  sui:)erficial  origin  these  two  divisions  extend  obliqueh' 
upward  and  forward  across  the  summit  of  the  petrous  pcjrtion  of  the 
temporal  bone,  and  pass  through  an  o\al  opening  in  the  dura  mater 
into  the  middle  fossa  of  the  brain-case.  The  larger  posterior  sensory 
root  terminates  in  the  semilunar,  which  is  situated  in  a  depression  on 
the  superior  part  of  the  anterior  surface  near  the  apex  of  the  petrous 
portion  of  the  temporal  bone.  This  ganglion  is  broad,  flattened,  and 
somewhat  crescent-shaped.  Its  convexity  is  directed  forward  and 
slightly  upward.  The  cells  of  this  ganglion  are  unipolar  in  shape.  Its 
surfaces  are  striated,  and  it  receives  on  its  inner  side  filaments  of  com- 
munication from  the  carotid  plexus  of  the  sympathetic  nervous  system. 

From  the  anterior  or  concave  margin  of  the  ganglion  the  three  large 
{li\isions  of  the  trigeminal  nerve  commence.  It  is  from  this  that  the 
nerve  receives  its  name. 

The  ophthalmic,  or  first  division  of  the  trigeminal  nerve,  is  the 
smallest  of  the  three  cords,  being  but  about  an  inch  in  length.  Its 
function  is  to  impart  sensation  to  the  eyeball,  the  lacrimal  gland,  the 
mucous  lining  of  the  eye,  and  a  portion  of  the  nose,  the  eyebrow  and 
forehead.  It  commences  from  the  upper,  inner,  and  anterior  portion 
of  the  margin  of  the  semilunar  ganglion.  It  is  a  flattened  cord,  and 
passes  forward  along  the  outer  wall  of  the  cavernous  sinus,  and  termi- 
nates before  or  just  as  it  is  about  to  pass  through  the  supraorbital 
fissure  by  dividing  into  three  main  branches,  the  frontal,  lacrimal,  and 
nasal,  which  are  distributed  as  their  names  indicate. 

Branches  of  the  Ophthalmic  Xerve. — 

Those  within  the  ca\ernous  sinus,  Lacrimal, 

Frontal,  Nasociliar\'. 


142  THE  MOUTH 

The  frontal  nerve  is  the  largest  of  the  branches  given  off  by  the 
ophthalmic,  and  is  in  reality  its  axial  continuation.  It  enters  the  orbit 
through  the  most  superior  portion  of  the  supraorbital  fissure,  and 
passes  forward  in  the  median  line  above  the  muscles  and  below  the 
periosteum.  It  terminates  midway  between  the  apex  and  base  of  the 
orbital  cavity,  above  the  levator  palpebrae  superioris,  by  dividing  into 
two  branches  of  unequal  size,  the  supratrochlear  and  the  supraorbital. 

The  supratrochlear  nerve  is  much  the  smaller  of  the  two  terminal 
branches  of  the  frontal.  It  extends  obliquely  inward  and  forward  over 
the  trochlear  muscle,  passing  out  of  the  orbit,  and  curving  around 
the  supraorbital  arch  between  the  supraorbital  foramen  and  the  troch- 
lear fossa.  It  then  extends  beneath  the  corrugator  and  frontalis 
muscles,  and  divides  into  two  terminal  branches.  These  branches 
pierce  the  orbicularis  and  frontalis  muscles,  supplying  them  as  well  as 
the  integument;  also  the  lower  and  median  portion  of  the  forehead, 
interlacing  with  the  corresponding  nerve  of  the  opposite  side.  This 
nerve  also  gives  off  two  distributing  branches,  one  extending  from  the 
nerve  near  the  trochlear  muscle,  which  passes  downw^ard  and  joins  the 
infratrochlear  branch  of  the  nasociliary  nerve,  and  the  other  near  its 
exit  from  the  orbit,  which  passes  to  the  eyelid  and  bridge  of  the  nose. 

The  supraorbital  nerve  is  really  a  continuation  of  the  frontal.  It 
passes  forward,  and  emerges  from  the  orbit  through  the  supraorbital 
notch  or  foramen.  It  then  curves  upward  on  the  forehead,  and  divides 
into  a  median  and  a  lateral  branch,  which  pierce  the  muscles  and  become 
the  cutaneous  nerves.  Its  branches  of  distribution  are  several  small 
cords  which  descend  to  the  structures  of  the  upper  eyelid,  and  one 
which  passes  outward  under  the  orbicularis  oculi,  interlacing  with 
the  facial  nerve.  The  muvscular  branches  are  distributed  to  the  cor- 
rugator, frontalis,  and  orbicularis  oculi.  The  cutaneous  branches 
are  two  in  number,  median  and  lateral.  These  extend  posteriorly  as 
far  as  the  occiput.  The  deep  or  pericranial  branches  are  distributed 
to  the  frontal  and  parietal  bones.  This  nerve  also  sends  a  filament 
which  supplies  the  mucous  membrane  of  the  frontal  sinus.  Occasion- 
ally the  division  of  the  supraorbital  nerve  takes  place  within  the 
orbit,    the   larger   branch    passing   through    the   supraorbital   foramen, 


SEASORV   XJMV/-:  SirPLV  OF   TEETH   AM)  TACE  143 

while   the  smaller   hr.iiich   extends   iiilenialK-   aroiiiid    the   supraorbital 
arch  or  throu.uh  tlu'  froiilal  uolch,  which  is  occasionalK-  present. 

The  hicrinud  nerve  is  the  smallest  of  the  three  branches  of  the 
oi)hthalmir.  It  passes  alon,u  the  outer  side  of  the  frontal  nerve  into 
the  orbit  through  the  anterior  foramen  lacerum,  encased  in  an  indi- 
vidual sheath  derived  from  the  dura  mater.  It  passes  forward  and 
outward  near  the  ])eriosteum  of  the  orbit  abo\  e  the  Rectus  lateralis 
to  the  lacrimal  fossa  of  the  frontal  bone,  accompanied  b>-  the  lacrimal 
arter>\  It  then  penetrates  the  external  tendo  oculi  and  terminates 
in  the  upper  eyelid. 

Branches  of  Distributio)!. — On  approaching;  the  lacrimal  fossa  the 
lacrimal  nerve  sends  a  communicating  cord  to  the  zygomaticotemporal 
branch  of  the  maxillary  nerve.  This  branch  occasionally  passes  back- 
ward through  a  canal  in  the  outer  wall  of  the  orbit,  its  divisions  form- 
ing an  arch  from  which  branches  are  distributed  to  the  lacrimal  gland 
and  the  conjunctiva.  Within  the  lacrimal  fossa  it  sends  branches  to 
the  lacrimal  gland  and  the  conjunctiva. 

The  nasociliary  nerve  is  intermediate  in  size  between  the 
other  two  branches  of  the  ophthalmic  nerve.  It  commences  from  the 
under  surface  of  the  ophthalmic  nerve,  and  passes  through  the  widest 
portion  of  the  foramen  lacerum  into  the  orbit  between  the  two  heads 
of  the  Rectus  lateralis,  accompanied  by  the  fourth  nerve.  On  either 
side  of  it  are  the  two  branches  of  the  third  nerve.  From  the  foramen 
it  passes  obliquely  inward  and  forward  over  the  optic  nerve  below 
the  Rectus  superior  and  Obliquus  superior  to  the  anterior  ethmoidal 
foramen  on  the  inner  wall  of  the  orbital  cavity.  It  here  di\ides  into 
the  internal  nasal  and  infratrochlear  nerves. 

Branches  of  the  Xasociliary  Xerve. — 

Branch  to   the  dura   mater.  Long  ciliary, 

Communicating  branches  to  Sphenoethmoidal, 

sympathetic  nerve,  Internal  nasal, 

Ganglionic,  Infratrochlear. 

The  branch  to  the  dura  mater  is  a  small  filament  which  turns  back- 
ward and  is  distributed  to  the  dura  mater  of  the  anterior  cerebral 
fossa. 


144  THE  MOUTH 

The  cotiumiuicatiug  branches  to  the  sympathetic  are  a  few  distinct 
lilaments  which  communicate  with  the  sympathetic  network  about  the 
ophthahiiic  artery  (Allen). 

The  ganglionic  branch  is  quite  slender  and  about  half  an  inch  in 
length.  It  usually  commences  from  the  nasociliary  as  it  extends 
between  the  two  heads.  It  passes  along  the  outer  side  of  the  optic 
nerve,  and  terminates  at  the  posterior  portion  of  the  ciliary  ganglion, 
constituting  its  long  or  sensory  root. 

The  long  ciliary  nerves  are  two  or  three  in  number,  and  com- 
mence from  the  nasociliary  as  it  extends  across  the  optic  nerve.  They 
pass  along  the  inner  margin  of  this  nerve,  and  unite  with  some  of  the 
short  ciliary  nerves  from  the  ciliary  ganglion.  They  then  pierce  the 
sclera  of  the  eye,  pass  forward  between  it  and  the  choroid,  and  are 
distributed  to  the  ciliary  muscles,  the  cornea,  and  the  iris. 

The  spheno-ethmoidal  (Luschka)  or  posterior  ethmoidal  (Krause) 
nerve  passes  from  the  nasociliary  to  the  posterior  ethmoidal  foramen 
(posterior  internal  orbital  canal),  and  is  distributed  to  the  mucous 
membrane  of  the  sphenoidal  sinus  and  the  posterior  ethmoidal  cells  in 
front  of  the  body  of  the  sphenoid  bone. 

The  internal  nasal  or  ethmoidal  nerve  is  in  the  line  of  continuation 
of,  and  generally  described  as,  the  nasociliary  nerve.  It  passes  through 
the  anterior  ethmoidal  foramen,  situated  between  the  frontal  and 
ethmoidal  bones,  into  the  brain-case,  just  external  to  the  cribriform 
plate.  It  then  extends  in  a  shallow  groove  along  the  outer  wall  of  the 
plate  to  the  cerebronasal  slit  near  the  crista  galli,  passes  through  this 
slit,  enters  the  nasal  cavity,  and  divides  into  three  branches — the 
internal  or  septal  branch,  the  lateral,  and  the  anterior  superficial 
branch. 

The  internal  or  septal  branch  of  the  internal  nasal  nerve  passes 
downward  and  forward,  and  supplies  the  anterior  portion  of  the  septum 
of  the  nose. 

The  lateral  branches  of  the  internal  nerve  usually  comprise  two  or 
three  filaments  which  are  distributed  to  the  anterior  portions  of  the  lat- 
eral walls  of  the  nasal  cavity,  including  the  extremities  of  the  middle 
and  inferior  concha  bones. 


SENSORY  NERVE  SUPPLY  OP   TEETH  AND  FACE  14.") 

'f/ic  (Ulterior  or  siiprrjicidl  hnnich  j)asses  downward  in  a  loiii^ilu- 
dinal  i^rooxc  or  ranal  on  llu-  internal  surfacx'  of  the  nasal  bone  until 
it  reaches  the  lateral  cartilage  of  the  nose.  Here  it  extends  between 
the  bone  and  the  cartilacic,  runs  beneath  the  nasalis,  and  becomes 
sui)erlicial,  terniinaling  in  the  spine,  the  wing,  and  the  tij)  of  the  nose. 

The  infratrochlear  nerve  is  one  of  the  terminal  branches  of  the  naso- 
ciliar>',  it  being  given  off  near  the  anterior  ethmoidal  foramen.  It  passes 
forward  along  the  inferior  border  of  the  ol)liquus  superi(jr,  and  parallel 
to  the  supratrochlear  nerve,  and  receives  a  communicating  branch 
from  it.  As  it  approaches  the  trochlea  it  passes  to  the  inner  angle 
of  the  eye  and  divides  into  two  sets  of  branches.  Those  of  the  sui:)eri(jr 
set  are  distributed  to  the  superficial  structures  of  the  superior  eyelid; 
while  those  of  the  inferior  set  are  distributed  to  the  superficial  structures 
at  the  root  and  side  of  the  nose,  the  superficial  portion  of  the  inferior  eye- 
lid, the  caruncle,  conjunctiva,  the  Uicrimal  sac,  and  the  lacrimal  duct. 

Variations. — "The  nasociliary  nerve  occasionally  (frequently, 
Krause)  gives  filaments  to  the  superior  and  internal  recti.  A  branch 
to  the  levator  palpebrae  superioris  has  been  met  with  (Fasebeck) ; 
offshoots  from  the  nerve  as  it  traverses  the  anterior  internal  orbital 
canal  to  the  frontal  sinus  and  ethmoidal  cells  are  described  by  Meckel 
and  Langenbeck." 

Maxillary  Nerve. — The  maxillary  or  second  division  of  the  trigeminal 
nerve  is  the  second  in  size  of  its  three  great  divisions.  It  is  composed 
entirely  of  sensory  fibers,  and  gives  sensation  to  nearly  all  the  struc- 
tures of  and  around  the  superior  maxillary  bone.  It  commences 
in  the  centre  of  the  convex  or  anterior  margin  of  the  semilunar  ganglion 
by  a  flattened  and  plexiform  band,  passes  horizontally  and  directly 
forward,  and  leaves  the  cranium  through  the  foramen  rotundum  in 
the  great  wing  of  the  sphenoid  bone.  It  then  enters  the  pter>'gopaIa- 
tine  fossa,  and  becomes  more  rounded  and  firmer  in  texture.  It  passes 
across  this  fossa  surrounded  by  adii:)ose  tissue,  and  enters  the  infraorbital 
groove,  and  receives  the  name  of  infraorbital  nerve.  It  then  passes 
through  this  canal,  and  emerges  upon  the  face  through  the  infraorbital 
foramen.  The  branches  of  this  nerve  can  be  divided  into  four  groups, 
according  to  the  locality  of  their  origin. 

10 


146  THE  MOUTH 

The  Zygomatic  branch  is  a  small  nerve  which  arises  from  the  upper 
portion  of  the  maxillar}'  nerve  just  after  it  emerges  from  the  foramen 
rotundum.  It  passes  forward  into  the  orbital  cavity  through  the 
pterygopalatine  fissure,  and  immediately  divides  into  two  branches, 
temporal  and  zygomatic. 

The  zygomaticotemporal  branch  passes  forward  in  a  groove  on  the 
outer  wall  of  the  orbit  until  it  reaches  the  temporal  canal  in  the  zygo- 
matic bone.  It  passes  through  this  canal  into  the  anterior  portion 
of  the  temporal  fossa,  ascends  between  the  bone  and  the  temporal 
muscle  a  short  distance,  pierces  the  muscle  and  its  aponeurosis  about 
an  inch  above  the  zygoma,  and  terminates  in  filaments  which  supply 
the  cutaneous  structures  of  the  temporal  region  and  the  side  of  the 
forehead.  It  interlaces  with  the  facial  and  occasionally  with  the  third 
division  of  the  fifth  nerve.  That  portion  of  the  nerve  within  the  orbit 
sends  one  or  two  filaments  of  communication  to  the  lacrimal  nerve, 
a  branch  of  the  ophthalmic  division  of  the  trigeminal. 

The  zygomaticofacial  {malar)  branch  at  its  commencement  passes 
through  the  loose  adipose  tissue  at  the  lower  angle  of  the  orbit  to  the 
z^-gomatic  bone,  through  which  it  extends  and  emerges  upon  the  face 
usually  by  two  branches.  It  is  distributed  to  the  cutaneous  tissues 
in  the  region  of  the  cheek,  and  interlaces  with  the  facial  nerve. 

The  sphe7io palatine  branches  are  usually  two  in  number,  and  are 
given  ofif  from  the  middle  of  the  lower  surface  of  the  pterygomaxillary 
portion  of  the  second  division  of  the  trigeminal  nerve.  They  pass 
downward  to  the  sphenopalatine  or  Meckel's  ganglion. 

The  Superior  Alveolar  Nerve. — The  superior  alveolar  nerve  branches 
from  the  maxillary'  in  the  pterygopalatal  fossa  before  it  enters  the 
infraorbital  groove,  and  just  after  two  branches  go  to  the  spheno- 
palatal  ganglion.  The  nerve  passes  downward  along  the  zygomatic 
surface  of  the  maxilla.  A  little  above  the  tuberosity  its  branches 
enter  one  or  more  foramina  and  pass  into  the  maxillary  sinus,  part 
of  the  nerves  supplying  the  walls  and  mucous  membrane.  The  main 
portion  enters  a  groove  in  the  outer  wall  and  passes  into  a  canal 
as  it  enters  the  anterior  wall  of  the  sinus.  The  superior  alveolar 
nerve  gives  off  branches  to  the  three  maxillary  molars,  two  premolars 


SENSORY  NERVE  SLPPLV  OF  TEETH  AM)  FACE  147 

and  caiiiiu',  and  w  illi  its  hraiiclK-s  supplies  not  only  the  maxillary  lecth 
hut  also  ihc  aKeolar  pnjccss,  the  gum  tissue,  the  investing  membrane 
of  the  roots  of  the  teeth  and  sockets,  the  mucous  membrane  and  bone 
of  the  floor  of  the  sinus.  The  incisor  teeth  are  more  than  hkeh'  supplied 
b>  the  arteries  and  nerves  belonging  to  the  original  incisive  bud. 
The  arteries  anastomose  with  one  another  no  matter  what  their  origin 
be,  but  the  ner\es  do  not,  though  they  interlace  with  each  other. 

The  Infraorbital  Nerve. — After  the  maxillary  nerve  enters  the 
infraorbital  groove  it  passes  along  the  floor  of  the  orbit,  and  through 
the  infraorbital  canal  terminating  at  the  infraorbital  foramen,  where 
it  divides  into  three  sets  of  branches. 

The  inferior  palpebral  branch  is  generally  made  up  of  two  nerves. 
They  ascend  in  a  groove  or  canal,  pass  through  the  upi)er  portion  of 
the  elevator  muscle  of  the  upper  lip,  and  are  distributed  to  the  orbic- 
ularis oculi,  the  skin,  the  conjunctiva  of  the  lower  eyelid,  and  interlace 
at  the  outer  angle  of  the  orbit  with  the  zygomaticofacial  and  facial 
nerves.  A  branch  also  passes  inward  and  interlaces  with  the  external 
nasal  nerve,  a  division  of  the  ophthalmic. 

The  nasal  or  internal  branches,  two  or  three  in  number,  are  dis- 
tributed to  the  skin  of  the  nose  and  the  lining  membrane  of  the  nostril, 
and  interlace  with  the  nasociliary  nerve. 

The  superior  labial  or  descending  branches  are  more  numerous 
than  the  branches  of  the  other  sets  from  the  infraorbital  nerve.  They 
pass  downward  beneath  the  Quadratus  labii  superioris  muscle,  and  are 
distributed  to  the  upper  lip,  its  skin,  mucous  (labial)  glands,  and  mucous 
membrane.    They  also  extend  to  the  anterior  portion  of  the  gums. 

The  infraorbital  plexus  of  ner\-es  is  situated  below  the  orbit,  and  is 
composed  of  branches  from  the  infraorbital  and  facial  nerves. 

The  Mandibular  Nerve. — The  mandibular  nerve  is  the  largest  of 
the  three  di\isions  of  the  trigeminal  nerve.  It  differs  from  the  other 
two  in  the  fact  that  its  function  is  mixed,  being  both  sensory-  and  motor; 
it  also  probably  supplies  in  a  measure  the  special  sense  of  taste.  This 
nerve  is  distributed  to  the  lower  portion  of  the  face,  the  mandible, 
and  mandibular  teeth,  a  portion  of  the  tongue,  and  the  muscles  of 
mastication. 


148  THE  MOUTH 

The  sensory  (or  larger)  portion  arises  from  the  inferior  lateral  and 
anterior  part  of  the  margin  of  the  semilunar  ganglion.  It  passes  down- 
ward through  the  foramen  ovale  in  the  sphenoid  bone,  accompanied 
by  the  smaller  anterior  or  motor  root.  Immediately  after  its  exit  from 
this  foramen  the  two  portions  unite,  their  fibers  interlacing,  to  form  one 
nerve,  the  mixed  function  of  the  nerve  being  thus  accounted  for.  It 
then  descends  vertically  to  the  pterygoideus  externus,  and  divides 
into  two  sets  of  branches,  anterior  and  posterior. 

The  anterior  motor  branch  or  trunk  of  the  maxillary  nerve  is  the 
smaller  of  the  two,  and  is  composed  almost  entirely  of  motor  fila- 
ments, which  are  distributed  to  the  muscles  of  mastication.  It  is 
divided  into  four  branches: 

Deep  temporal,  External  pterygoid, 

Masseteric,  Buccinator. 

The  deep  temporal  branches  are  usually  two  in  number,  though 
occasionally  there  are  three — anterior,  middle,  and  posterior. 

The  anterior  branch  before  piercing  the  pterygoideus  externus  is 
joined  by  a  communicating  filament  from  the  buccal  nerve.  It  ascends 
across  the  pterygoid  ridge  of  the  sphenoid  bone,  passes  to  the  anterior 
portion  of  the  temporal  fossa,  and  supplies  that  part  of  the  temporalis 
situated  in  this  region. 

The  deep  temporal  branch  passes  outward  above  the  pterygoideus 
externus,  then  curves  upward,  running  close  to  the  temporal  bone, 
and  is  distributed  to  the  deep  and  internal  portions  of  the  tem- 
poralis. 

The  posterior  temporal  branch  is  made  up  entirely  of  motor  fila- 
ments. During  the  first  portion  of  its  course  it  is  often  associated  with 
the  masseteric  nerve.  It  passes  in  a  tortuous  manner  upward  and  out- 
ward, then  upward  through  the  proximal  surface  of  the  temporalis; 
it  passes  out  of  this  muscle  and  through  its  fascia  from  a  half  to 
three-quarters  of  an  inch  above  the  zygoma,  and  then  turns  upward 
beneath  the  skin  and  interlaces  with  the  auriculotemporal  and  facial 
nerves. 

The  masseteric  nerve  is  larger  than  the  deep  temporal,  and  arises  in 
close  proximity  to  it.    Occasionally  these  two  nerves  arise  as  a  common 


SENSORY  NERVE  SUPPLY  OF   TEETII  AND  FACE  149 

Iriiiik  from  the'  third  (h\  isioii  of  tlic  fiftli  ncr\'c.  It  i)asses  backward 
and  outward  between  thi'  ui)iH'r  j)()rtion  of  the  z>'j;(>matic  fossa  and  the 
superior  border  of  the  i3terygoideus  externus,  curves  slightl>'  d(j\vn- 
ward  and  outward,  and  passes  throuj^h  the  mandibular  notch  in  the 
nunuHbuhu'  bone.  It  then  extends  downward  between  the  ramus  of 
the  l)(>ne  and  the  masseter  muscle,  to  which  muscle  it  is  mainly  dis- 
tributed. Its  other  branches  of  distribution  are,  first,  a  small  com- 
municating; filament  which  interlaces  with  the  deep  temjjoral,  and 
an  articulating;  branch  which  passes  to  the  mandibular  articu- 
lation. 

The  iiiter/Kil  ptiry<^oid  nerve  is  the  shortest  branch  of  the  third 
division  of  the  trigeminal  nerve.  It  is  given  off  from  its  anterior  and 
proximal  side  on  a  level  with  the  otic  ganglion.  It  passes  backward 
between  the  ganglion  and  the  lingual  nerve,  occasionally  extending 
through  the  ganglion  to  the  inner  side  of  the  pterygoideus  internus,  to 
which  it  is  mainly  distributed.  Its  other  branches  of  communication 
are,  first,  a  motor  root  to  the  otic  ganglion;  second,  a  filament  to  the 
tensor  palati;  third,  a  branch  to  the  tensor  tympani. 

The  external  pterygoid  nerve  is  not  constant  in  its  origin;  it  seldom 
arises  from  the  main  trunk  of  the  inferior  maxillary,  but  generally  in 
conjunction  with  the  buccal  branch  or  from  the  internal  pterygoid 
nerve.     It  is  distributed  to  the  pterygoideus  externus  muscle. 

The  buccinator  nerve,  though  described  under  the  head  of  the  motor 
branches  of  the  mandibular  nerve,  is  almost  entirely  composed  of  sen- 
sory fibers.  It  arises  from  the  lateral  margin  of  the  main  trunk  of  the 
mandibular  nerve  by  from  one  to  three  bundles,  and  is  usually  joined 
at  its  origin  by  the  anterior  deep  temj^oral  and  the  external  ptenygoid 
nerves.  It  passes  outward,  either  between  the  two  heads  of  the  ptery- 
goideus externus  or  between  the  two  pterygoid  muscles;  extends  down- 
ward to  the  inner  surface  of  the  coronoid  process  of  the  mandible, 
thence  forward  between  this  process  and  the  tuberosity'  of  the  maxilla, 
occasionally  passing  between  the  fibers  of  the  temporal  muscle  close 
to  its  insertion.  Midway  between  the  lobe  of  the  ear  and  the  angle 
of  the  mouth  it  becomes  superficial,  and  terminates  b}-  di\iding  into 
superior  and  inferior  branches. 


150  THE  MOUTH 

Branches  of  distribution  are — 

(a)  Two  or  three  external  pterygoids,  which  are  given  off  as  the  nerve 
passes  through  the  pterygoideus  externus. 

{b)  An  anterior  deep  temporal  bra^tch,  which  usually  joins  the  deep 
temporal  ner\'e.  It  passes  upward  to  the  thick  portion  of  the 
temporalis. 

{c)  A  descending  branch,  which  passes  to  the  insertion  of  the 
temporalis. 

{d)  Superior  terminal  branches,  which  supply  the  upper  portion  of 
the  buccinator  muscle,  the  skin  of  the  zygomatic  and  buccal  region. 
These  branches  interlace  with  the  facial  nerve  near  the  parotid  duct. 

(e)  I?iferior  terminal  branches,  which  pass  forward  to  the  angle  of  the 
mouth,  and  are  distributed  to  the  skin,  the  lower  portion  of  the  buc- 
cinator muscle  and  the  buccal  mucous  membrane  and  glands.  These 
branches,  together  with  buccal  branches  of  the  facial  nerve,  form  a 
plexus  around  the  facial  vein. 

The  posterior  or  sensory  branches  of  the  third  division  of  the  fifth 
nerve  are — 

Auriculotemporal,  Mandibular. 

Lingual, 

The  auriculotemporal  nerve  usually  arises  by  two  roots,  of  unequal 
size,  situated  close  to  the  foramen  ovale.  At  first  they  pass  backward 
and  outward,  one  on  either  side  of  the  middle  meningeal  artery.  They 
then  unite  and  form  a  flattened  trunk,  which  passes  back  beneath 
the  pterygoideus  externus  to  the  inner  side  of  the  neck  of  the  condyle. 
It  cur\^es  around  the  condyle  in  company  with  the  superficial  temporal 
artery,  passes  upward  between  the  ear  and  the  mandibular  articula- 
tion, thence  over  the  zygoma  and  beneath  the  superficial  temporal 
artery,  terminating  in  several  filaments  which  are  distributed  to  the 
skin  over  the  greater  portion  of  the  temporal  region,  extending  to  its 
superior  extremity.     They  interlace  anteriorly  with  the  facial  nerve. 

Branches  of  the  auriculotemporal  nerve  are — 
Communicating,  Parotid, 

Articular,  Anterior  auricular. 

Branches  to  external  acoustic  meatus, 


SENSORY  NERVE  SUP  PLY  OF   TEK'ni  AM)  FACE  151 

The  coHiiiiiiiiicdliiii^  hrdiir/ics  arc  sIcikUt  lilanu-nls  wliich  i)as.s 
between  tlie  otic  ganglion  and  tlu-  third  dixision  of  ihv  iilth  ner\e  near 
its  origin.  One  or  two  branches  which  are  given  off  near  the  neck  of 
the  condyle  of  the  Unver  jaw  pass  forward  beneath  the  facial  nerve, 
unite  with  it  near  the  posterior  border  of  the  niasseter  muscle,  and  form 
one  of  the  principal  communicating  branches  between  the  facial  and 
trifacial  nerves. 

llie  articular  branches  are  one  or  two  fine  filaments  which  ])ass  to 
the  mandibular  articulation. 

7V/('  branches  to  the  external  acoustic  meatus  are  two  in  number, 
superior  and  inferior.  They  pass  between  the  bone  and  the  cartilage  to 
enter  the  meatus,  and  are  distributed  to  the  lining  of  the  ear.  The 
superior  branch  gives  off  a  filament  to  the  tympanic  membrane. 

The  parotid  brandies  supply  the  parotid  gland.  They  are  frequently 
connected  with  the  facial  nerve. 

The  anterior  auricular  branches  are  usuall>'  two  in  number.  They 
pass  between  the  tragus  and  helix,  and  are  distributed  to  the  concave 
surface  of  the  auricle. 

The  Lingual  Nerve. — The  lingual  nerve  is  second  in  size,  and  is 
an  important  l)ranch  of  the  third  division  of  the  trigeminal.  From  its 
origin  it  passes  down  on  the  internal  surface  of  the  pterygoideus  ex- 
ternus,  anterior  and  a  little  to  the  inner  side  of  the  mandibular  nerve. 
These  two  nerves  have  been  observed  arising  from  a  common  trunk  and 
bifurcating  near  the  mandibular  foramen.  As  the  lingual  ner\'e  reaches 
the  lower  border  of  the  muscle  it  curves  forward  between  the  ptery- 
goideus internus  and  the  ramus  of  the  lower  jaw,  and  inclines  inward 
over  the  superior  constrictor  of  the  pharynx,  under  the  styloglossus 
muscle  and  above  the  deep  jxjrtion  of  the  submaxillary  mucosali\ary 
gland,  it  then  extends  forward,  crosses  the  submaxillary  duct,  ])asses 
below  the  mucous  membrane  of  the  alv^eolar  lingual  groo\e,  and  ter- 
minates at  the  apex  of  the  tongue. 

Branches  of  Communication. — Near  the  origin  of  the  lingual  nerve  a 
communicating  branch  passes  over  the  internal  maxillary  artery  to  the 
mandibular  nerve.  There  is  also  a  small  branch  which  passes  to 
the  hypoglossal  nerve.     This  nerve  also  forms  a  plexus,   from  which 


152  THE  MOUTH 

branches  are  distributed  to  the  walls  of  the  internal  jugular  vein,  a 
portion  of  the  sinuses  and  the  cancelli  of  the  occipital  bone,  and  inter- 
lace with  branches  which  pass  through  the  anterior  condyloid  foramen. 
The  chorda  tympani  branch,  which  is  a  small  nerve,  arises  from  the 
facial,  and  descends  from  the  proximal  extremity  of  the  petrot^^mpanic 
suture  to  the  acute  angle  of  the  lingual  nerve  as  it  passes  forward  close 
to  the  lower  border  of  the  pterygoideus  externus.  At  first  there  is 
only  mechanical  union  between  these  two  nerves,  but  subsequently  they 
are  intimately  associated.  Branches  pass  directly  to  the  submaxillary 
ganglion  where  it  is  in  close  relation  wdth  the  submaxillary  mucosali- 
vary  gland.  Anterior  to  the  last  branch,  one  or  two  communicating 
filaments  descend  over  the  first  portion  of  the  hypoglossal  muscle  to 
interlace  with  filaments  from  the  hypoglossal  nerve. 

The  branches  of  distribution  of  the  lingual  nerve  are — 

A  small  branch  to  the  palatoglossal  fold  (anterior  palatine  arch)  and 
the  tonsils. 

A  sublingual  branch,  which  is  distributed  to  the  mucous  membrane 
of  the  floor  of  the  mouth,  the  gum  tissue  on  the  inner  surface  of  the 
mandible,  and  the  sublingual  mucous  gland. 

The  lingual  or  tenninal  branches,  which  pass  upward  between  the 
fibers  of  the  tongue,  divide  into  finer  filaments,  which  are  distributed 
to  the  mucous  membrane  of  the  anterior  two-thirds  of  the  tongue  and 
terminate  in  the  conical  and  fungiform  papillae. 

A  few  ftexiform  filaments,  which  pass  beneath  the  tongue,  some 
terminating  on  the  under  surface  of  the  tip  and  in  the  glands  of  Niihn. 

The  Inferior  Alveolar  Nerve. — The  inferior  alveolar  nerve  is  the  largest 
of  the  branches  of  the  third  or  mandibular  division  of  the  trigeminal 
nerve  (Fig.  130).  From  its  origin  it  passes  downward,  accompanied  by 
the  inferior  alveolar  artery,  on  the  external  surface  of  the  pterygoideus 
externus,  posterior  and  a  little  to  the  side  of  the  lingual  nerve.  After 
reaching  the  lower  border  of  the  muscle,  it  passes  between  the  .spheno- 
mandibular  ligament  and  the  ramus  of  the  mandible,  and  enters  the 
mandibular  canal  or  tube  (see  page  11)  from  which  there  are  small 
lateral  tubes  which  serve  as  nerve  and  vessel  conduits  to  the  roots  of 
all  the  mandibular  teeth  and  surrounding  tissue.     In  the  region  of  the 


SENSORY  NERVE  SUPPLY  OF   TEETH  AM)  PACE 


153 


canine  toolli  tlic  ner\e  (li\  ide-s  into  incisor  and  nicnlai  branches,  the 
former  going  to  the  incisor  teeth.  Tlie  latter  turns  l^ack  ujxjn  itself, 
passes  along  the  mental  canal  and  out  b\-  the  mental  foramen. 

The  branches  of  the  inferior  alveolar  nerve  are — 

.1  comiiiiiuicatiug  branch,  which  passes  over  the  internal  maxil- 
lar\-  arter\-  to  the  lingual  nerve. 


Termi ruit  ion  of 

nasopdlaiine 

nerve 


Fig.  129. — The  sphenopalatine  ganglion  and  its  branches.     (Gray.) 

A  mylohyoid  branch,  which  is  generally  described  with  the  inferior 
alveolar,  which  is  a  sensory  nerve,  while  the  former  is  in  reality 
motor  in  character.  Its  fibers  can  be  traced  from  its  point  of  distribu- 
tion backward  to  the  anterior  or  motor  root  of  the  trigeminal  It  is 
given  off  from  the  inferior  alveolar  nerve  just  as  it  is  about  passing  into 
the  mandibular  foramen,  and  passes  downward  and  forward,  accom- 
panied by  the  mylohyoid  artery  in  the  mylohyoid  groove  of  the 
mandible.  It  is  distributed  to  the  inferior  surface  of  the  mylohyoid 
and  the  anterior  belh'  of  the  digastric,  also  the  tensor  palati  and  tensor 


154  THE  MOUTH 

tympani  muscles.  A  few  filaments  from  this  branch  pass  through  the 
myloh^'oid  muscle  and  interlace  with  the  lingual  nerve.  Branches 
are  also  described  as  passing  to  the  triangularis  (depressor  anguli 
oris)  and  platysma  muscles  (Henle),  to  the  integument  below  the  chin 
(Krause  and  Schwalbe),  and  to  the  submaxillary  gland  (Meckel,  Henle, 
Curnow). 

The  ififerior  alveolar  branches  are  numerous,  and  fine  filaments 
pass  through  the  apical  foramina  in  the  roots  of  the  teeth  of  the  lower 
jaw  to  supply  the  pulp  and  tooth  w^ith  sensation.  There  are  also 
filaments  which  pass  upward  and  supply  the  alveolodental  membranes 
and  gum  tissue. 

The  incisor  branch  is  the  continuation  of  the  main  trunk  of  the 
inferior  ah^eolar  ner\-e. 

The  mental  or  labial  nerve  is  the  larger  of  the  two  terminal  divis- 
ions of  the  inferior  alveolar  nerve.  It  passes  outward  from  the  mental 
canal  through  the  mental  foramen,  and  immediately  breaks  up  into 
three  branches  beneath  the  triangularis  muscle.  The  inferior  branch 
descends,  and  is  distributed  to  the  chin.  The  two  superior  branches 
ascend  to  supply  the  lip,  its  mucous  membrane,  and  the  labial  glands. 
These  three  branches  freely  interlace  with  the  maxillary  branch  of  the 
facial  nerve. 


SYMPATHETIC  GANGLIA  CONNECTED  WITH  THE 
TRIGEMINAL  NERVE. 

The  sympathetic  ganglia  found  in  connection  with  the  trigeminal 
nerve  belong  to  the  general  sympathetic  system  found  throughout  the 
body.  This  sympathetic  system  is  composed  of  a  large  number  of 
ganglia,  cords,  and  plexuses. 

The  ganglia  are  separate  centres  for  the  conveyance  and  distribu- 
tion of  various  cords  and  filaments,  consisting  of  motor,  sensory,  and 
sympathetic  fibers.  They  contain  nerve  cells  very  similar  to  those 
found  in  the  encephalon  and  spinal  cord.  These  ganglia  are  arranged 
in  two  chains  situated  on  each  side  of  the  body  near  the  central  line. 
They  commence  with  the  ciliary  ganglion  in   the  orbit,   and   extend 


SYMPATHETIC  GAM.UA    COWJXTKJ)   11777/    Th'/CKM /.\A  L  \KRVE     155 

dowmvartl    akjiii;    each    side   ot    the    xerlcbral    foluiiui,    and    lerniinale 
below  in  the  gaiighon  inii)ar  in  tlie  ((K^^ygeal  region. 

The  ganglionic  or  symi)allu'lic  s\stcni  is  indciK-ndcnl  and  separate 
from  the  general  nervous  system,  but  is  intimately  connected  with  it  by 
communicating  branches  which  pass  fnim  the  motor  and  sensory  roots 
of  the  cerel)rosi)inal  nerves,  as  well  as  by  direct  filaments  which  extend 
between  it  and  the  cerebrospinal  centres.  The  sympathetic  nervous 
system  is  distributed  to  the  mucous  membranes,  the  viscera,  the  coats  of 
bloodvessels,  and  to  the  non-striated  or  involuntary  muscular  fibers. 
The  nerves  of  this  system  form  ])lexuses  in  vari(jus  jjarts  of  the  body, 
especially  around  the  arteries.  They  are  not  found  in  connection  with 
striated  xoluntary  muscular  fiber.  The  cardiac  muscle  being  partially 
striated,  yet  involuntary,  is  an  exception.  Numerous  ganglionic  cells 
are  found  situated  at  the  terminal  ends  of  sympathetic  nerve  fibers. 

The  four  pairs  of  ganglia  associated  with  the  trigeminal  nerve  are 
as  follows: 

Ciliary,  Otic, 

Sphenopalatine,  Submaxillary. 

The  ciliary  ophthalmic  or  lenticular  ganglion  is  situated  in  the 
posterior  portion  of  the  orbital  cavity,  between  the  Rectus  lateralis 
and  the  optic  nerve,  in  close  apposition  to  the  ophthalmic  artery.  It 
is  a  small,  flattened,  and  reddish  body,  surrounded  by  adipose  tissue, 
its  flattened  surfaces  being  the  proximal  and  the  distal.  It  measures 
about  2  mm.  in  length  anteroposteriorly. 

Its  branches  or  roots  of  communication  are — 

1.  The  sensory  or  long  root,  which  is  a  slender  filament  arising 
within  the  cavernous  sinus  from  the  nasociliary  nerve.  It  enters  the 
posterior  superior  angle  of  the  ganglion.  Occasionalh'  a  filament  is 
found  which  extends  from  the  lacrimal  nerve  to  the  ganglion. 

2.  The  motor  or  short  root,  which  is  shorter  and  thicker  than  the 
sensory  root,  and  occasionally  divides  into  two  branches.  It  is  derived 
from  the  inferior  oblique  branch  of  the  motor  oculi  or  third  ner\"e,  and 
joins  the  ganglion  at  its  posterior  inferior  angle. 

3.  The  sympathetic  or  middle  root,  which  is  derived  from  the  s>'stem 
to  which  the  ganglion  belongs.     This  root  is  smaller  than  either  of  the 


156  THE  MOUTH 

Others,  and  originates  in  the  cavernous  sinus,  being  derived  from  the 
carotid  plexus.  Through  this  plexus  it  communicates  with  the  cervi- 
cal ganglion.  As  it  extends  forward  to  the  posterior  border  of  the 
ganglion,  it  occasionally  unites  with  the  long  or  sensory  root,  forming  a 
common  trunk. 

Variations  in  the  Roots. — The  ciliary  ganglion  may  receive  acces- 
sory roots  from  the  superior  division  of  the  motor  oculi,  the  lacrimal, 
abducens,  or  sphenopalatine  ganglion  (Henle,  Tiedemann). 

"According  to  Reichart,  the  ciliary  ganglion  does  not  receive  its 
sympathetic  fibers  by  a  single  root,  but  by  several  fine  filaments,  the 
majority  of  which  accompany  the  motor  oculi. 

"It  appears  from  the  mode  of  development  and  arrangement  in 
many  of  the  lower  vertebrates  that  the  ophthalmic  ganglion  is  mor- 
phologically associated  more  intimately  with  the  motor  oculi,  having, 
in  fact,  the  significance  of  a  spinal  ganglion  of  that  nerve  (M.  Marshall, 
Schwalbe)."^ 

Its  branches  of  distribution  are  to  the  iris  and  ciliary  muscles.  The 
short  ciliar}^  nerves,  ten  to  fifteen  in  number,  arise  in  two  sets,  superior 
and  inferior. 

The  superior  set  arises  from  the  anterior  superior  angle,  and  passes 
forward,  in  a  wave-like  manner,  between  the  optic  nerve  and  the 
superior  rectus  muscle  to  the  posterior  part  of  the  eyeball. 

The  inferior  set  is  more  numerous  than  the  superior,  and  arises 
from  the  anterior  inferior  angle  of  the  ganglion.  It  passes  in  a  wave- 
like manner  below  the  optic  nerve  and  above  the  inferior  rectus  muscle 
to  the  posterior  part  of  the  eyeball.  It  is  accompanied  by  the  long  cili- 
ary nerves  w^hich  are  derived  from  the  nasal  branch  of  the  ophthalmic 
division  of  the  trigeminal.  One  or  more  of  its  fibers  join  the  short 
ciliary  nerves.  . 

Both  the  superior  and  the  inferior  sets  pass  forward  through  the 
sclera  of  the  eye  in  delicate  grooves  on  its  inner  surface,  next  to  the 
choroid,  and  are  distributed  to  the  ciliaris  muscle,  the  iris,  and  the 
cornea.  A  small  filament  penetrates  the  optic  nerve  to  the  arteria 
centralis  retinae  (Tiedemann). 

'  Quain's  Anatomy. 


SYMPATHETIC  GAMIIJA    CONNECTED   117  77/    TKICJiMINAL  NERVE     157 


Sphenopalatine  Ganglion.  Ihe  sphen()i)alaliiie  ganglion  (gan- 
glion of  Meckel)  (F'ig.  129)  isthelargestof  theganglia  associated  with  the 
trigeminal  nerve.  It  is  situated  in  the  pterygopalatine  fossa  in  front  of  the 
anterior  opening  (jf  the  pterygoid  canal,  close  to  the  sphenopalatine  fora- 
men.    It  is  triangular  in  form,  with  its  apex  pointing  backward  in  the 


A  uriculotcmporah 


Deep  temporal 


Masseteric 
Sphe  ruyrna  nd  ih  idar 
ligament 
Inferior  alveolar 
Mylohyoid 

Lingual 
Rarrms  of  man- 
dible {cut) 


Fig.  130. — The  pterygoidcus  cxternus  and  the  branches  of  the  nianchbular  nerve  in  relation  to  it. 

(Gray.) 

direction  of  the  pterygoid  canal,  and  is  surrounded  by  adipose  tissue.  Its 
outer  surface  is  convex,  and  averages  about  8  mm.  in  diameter.  It  is 
reddish-gra>'  in  color,  except  at  its  broadest  part,  where  it  is  com- 
posed entirely  of  gray  matter. 

The   branches  or    roots  of    communication  of  the  sphenopalatine 
ganglion  are — 


158  THE  MOUTH 

1.  The  sensory  roots,  two  in  number,  which  arise  from  the  maxil- 
lary nerve  as  it  passes  through  the  pterygopalatine  fossa.  They 
enter  the  ganglion  separately,  one  at  the  anterior  and  the  other  at  the 
posterior  corner  of  the  upper  surface.  Many  of  the  fibers  of  these 
roots  pass  through  the  ganglion  without  becoming  incorporated  with 
it,  and  receive  no  influence  from  it.  These  fibers  form  the  palatine 
nerves. 

2.  The  motor  root,  w^hich  is  quite  long,  and  arises  from  the  facial 
nerve  or  the  greater  superficial  petrosal  nerve  at  the  genicular  ganglion 
within  the  prominence  of  the  facial  canal.  From  this  point  it  passes 
forward  through  the  hiatus  on  the  anterior  surface  of  the  petrous  portion 
of  the  temporal  bone,  then  inward  beneath  the  semilunar  ganglion, 
being  separated  from  it  by  a  thin  layer  of  dura  mater.  It  then  pierces 
the  fibrocartilage  occupying  the  foramen  lacerum  and  passes  to  the 
outer  side  of  the  internal  carotid  artery.  At  this  point  it  is  joined  by 
the  sympathetic  root  or  the  large  deep  petrosal  nerve  of  the  spheno- 
palatine ganglion,  and  the  two  conjointly  are  called  the  nerve  of  the 
pterygoid  canal  (Vidian  nerve).  They  pass  into  the  pterygoid  canal 
in  the  sphenoid  bone,  extend  through  this  canal,  and  at  the  exit  enter 
the  posterior  or  apical  extremity  of  the  ganglion.  The  gray  matter  of 
the  ganglion  extends  along  the  nerve  as  far  as  the  origin  of  the  sympa- 
thetic at  the  carotid  plexus. 

3.  The  sympathetic  root,  or  the  large  deep  petrosal  nerve,  commences 
from  the  carotid  plexus  which  surrounds  the  internal  carotid  artery. 
These  filaments  unite  and  form  a  short  branch  of  reddish  color  and  soft 
texture,  which  passes  forward  and  joins  the  motor  root  of  the  ganglion 
to  form  the  nerve  of  the  pterygoid  canal  above  described.  Occasionally 
these  two  roots  remain  separate  throughout  their  course,  and  enter 
the  ganglion  ununited. 

The  branches  of  distribution  of  the  sphenopalatine  ganglion  are — • 
I.  Orbital  branches,  consisting  of  three  or  four  fine  filaments 
which  pass  into  the  orbit  through  the  inferior  orbital  fissure,  and  are 
distributed  to  the  periosteum  and  mucous  membrane  of  the  posterior 
ethmoidal  and  sphenoidal  sinuses  by  passing  between  the  sphenoid  and 
ethmoid  bones. 


SYMPATIII'JIC  cam;  LI  A    CONNECTED   117/7/    T  RKih.M  I  \  A  I.   M.RVE     159 

Some  of  llu'  hraiulu's  wliich  i)ass  upward  arc  distribiik-d  U)  llie 
lU'iirik'iniiia  of  tlic  optic  iicrve  (Arnold  and  Longct). 

A  branch  from  (he  .uant^lion  ascends  to  the  sixth  nerve  (Bock  and 
Valentin). 

Also  a  branch  to  the  ciliary  gani^lion  (Tiedemann). 

Two  or  three  branches,  sphenoethmoidal,  ascend  to  the  superior 
portion  of  the  internal  orl)ital  wall,  pass  through  the  i)osterior  ethmoidal 
foramen,  and  enter  the  brain-case  (Luschka). 

2.  The  descending  or  palatine  branches,  three  in  number  anterior 
posterior,  and  external.  These  three  branches  pass  from  the  maxillary 
nerve  through  that  portion  of  the  ganglion  in  which  there  is  little 
ganglionic  or  gray  matter.  They  thus  pass  to  their  distribution  with 
out  becoming  involved  or  influenced  by  the  ganglion,  excejit  it  be 
to  a  very  slight  extent. 

The  anterior  or  large  palatine  nerve  passes  downward  in  the 
pterygopalatine  canal,  and  enters  the  oral  cavity  at  the  great  palatine 
foramen.  It  then  passes  forward  in  a  groove  on  the  side  of  the  hard 
palate  to  its  anterior  portion,  where  it  joins  the  nasopalatine  nerve. 
It  is  distributed  to  the  gums,  mucous  glands,  and  membrane  of  the 
hard  palate.  This  nerve  gives  ofT  a  separate  branch  (middle  palatine), 
which  passes  downward  to  the  soft  palate  in  a  separate  canal.  It 
also  gives  ofif  branches  (inferior  nasal)  while  in  the  canal,  which  are 
distributed  to  the  middle  and  inferior  conchse. 

The  posterior  or  middle  palatine  nerve  pa3ses  downward,  accom- 
panied by  a  small  artery  in  the  small  palatine  canal,  to  the  soft  palate, 
and  divides  into  two  sets  of  branches.  One  set  is  distributed  to  the 
levator  palati  and  musculus  uvulae,  and  may  be  composed  entireK' 
of  motor  filaments  coming  from  the  great  superficial  petrosal  branch 
of  the  motor  and  facial  nerves,  and  the  nerve  of  the  pterygoid  canal. 
The  other  set,  which  is  sensory,  is  distributed  to  the  mucous  membrane 
of  the  superior  surface  of  the  soft  palate,  the  glands  of  the  soft  palate, 
and  to  the  tonsils. 

The  external  palatine  nerve  is  the  smallest  of  the  three  descending 
branches,  and  is  not  always  constant  in  its  existence.  It  jjasses  cknvn- 
ward  through  the  external  palatine  canal,  which  is  situated  between 


IGO  THE  MOUTH 

the  tuberosit>-  of  the  maxilla  and  palate  bones,  and  is  distributed  to 
the  tonsils,  uvula,  and  outer  portion  of  the  soft  palate. 

The  iutoiiaJ  or  nasal  branches  consist  of  two  divisions,  upper  nasal 
and  nasopalatine. 

The  upper  nasal  branches,  four  or  five  in  number,  are  small,  and 
pass  horizontalh'  inward  through  the  sphenopalatine  foramen  into  the 
posterior  superior  portion  of  the  nasal  chamber.  They  are  distributed 
to  the  posterior  superior  portion  of  the  nasal  septum,  to  the  mucous 
membrane  covering  the  superior  and  middle  conchae  and  to  the  posterior 
ethmoidal  cells. 

The  nasopalatine  branch  is  larger  than  the  upper  nasal  branches, 
and  is  an  important  division  of  the  nasal  nerves.  It  is  long  and  slender, 
and  arises  from  the  proximal  surface  of  the  sphenopalatine  ganglion. 
It  passes  through  the  sphenopalatine  foramen  across  the  roof  of  the 
nasal  cavity  to  the  septum,  where  it  turns  downward  and  forward, 
and  extends  in  a  groove  or  canal  on  the  vomer  to  the  foramina  of 
Scarpa  or  nasopalatine  foramina.  These  are  two  in  number,  anterior 
and  posterior,  and  are  situated  in  the  intermaxillary  suture.  The 
nerve  of  the  right  side  usually  passes  through  the  posterior  foramen, 
while  the  nerve  of  the  left  side  passes  through  the  anterior.  These 
two  nerves  (right  and  left  nasopalatine),  meeting  in  the  incisor  fora- 
men, form  a  fine  plexus,  from  which  minute  filaments  are  distributed 
to  the  palate  posterior  to  the  incisor  teeth  and  interlace  with  the  anterior 
or  great  palatine  nerve.  "In  the  course  along  the  septum  small  fila- 
ments are  furnished  from  the  nasopalatine  to  the  pituitary  membrane."^ 

The  posterior  branches  generally  assume  the  name  of  the  nerve  of 
the  pterygoid  canal  (already  described)  and  the  pharyngeal  nerve. 

The  pharyngeal  or  pterygopalatine  nerve  consists  of  several  fine 
filaments  which  frequently  arise  from  the  nerve  of  the  pterygoid  canal, 
instead  of  from  the  posterior  portion  of  the  ganglion.  It  passes  down- 
ward through  the  pterygopalatine  canal,  accompanied  by  an  artery 
of  the  same  name,  and  is  distributed  to  the  mucous  membrane  of  the 
upper  portion  of  the  pharynx  and  neighborhood  of  the  auditory  tube. 

'  Quain's  Anatomy. 


SYMPATHETIC  GAXCIJA    CO.WIXTK!)   WITH   TRICE.M I .\ AL  .\KR\K     Kil 

Otic  Ganglion.     Tlu'  otic  ganglion  (Fig.  131)  is  a  refl(lish-gra\  l)(j(ly 
situated  just  below   tlic  foramen  ovale,  and  in  (lose  a])j)osition  to  the 


Fig.  131. — The  otic  ganglion  and  its  branches.     (Gray.) 


11 


Fig.  132. — Diagram  showing  cutaneous  areas  of  face  and  scalp.     (Gray.) 


162  THE  MOUTH 

proximal  surface  of  the  mandibular  nerve  at  the  point  of  union  of  its 
motor  root  with  the  third  sensory  division  arising  from  the  semilunar 
ganglion,  with  the  cartilaginous  portion  of  the  auditory  tube  to  its  inner 
surface,  while  the  middle  meningeal  artery  passes  up  into  the  brain- 
case  just  posterior  to  it.  It  is  a  flattened  oval  body,  its  widest  diameter, 
which  is  about  one-sixth  of  an  inch,  being  anteroposterior. 
Its  branches  or  roots  of  communication  are — 

1.  The  lo?ig  or  sensory  root  of  Arnold  which  is  composed  of 
the  lesser  superficial  petrosal  nerve,  a  continuation  of  the  tympanic 
branch  of  the  glossopharyngeal,  and  a  branch  from  the  geniculate 
ganglion  of  the  seventh.  The  ganglion  also  receives  an  important 
sensory  branch  from  the  auriculotemporal  nerve  of  the  trigeminal. 

2.  The  motor  or  short  root  of  Arnold  which  is  derived  from  the 
internal  pterygoid  branch  of  the  inferior  maxillary  division  of  the 
trigeminal.  It  also  receives  motor  filaments  through  the  lesser  super- 
ficial petrosal  derived  from  the  genicular  ganglion  of  the  seventh 
nerve. 

3.  The  sympathetic  root,  which  is  derived  from  the  plexus  around 
the  middle  meningeal  artery. 

The  branches  of  distribution  of  the  otic  ganglion  supply  in  part  the 
parotid  gland,  the  chorda  tympani,  tensor  tympani,  tensor  veli  pala- 
tini muscles,  and  the  mucous  membrane  of  the  middle  ear. 

The  Submaxillary  Ganglion. — The  submaxillary  or  lingual  gan- 
glion is  situated  above  the  deep  portion  of  the  submaxillary  muco- 
salivary  gland,  close  to  the  outer  portion  of  the  hyoglossus  muscle. 
It  varies  in  shape  and  size,  usually  being  triangular,  but  occasionally 
it  is  fusiform  or  plexiform,  or  absent  altogether. 

Its  branches  or  roots  of  communication  are — 

1.  The  sensory  root,  which  arises  from  the  lingual  branch  of  the 
mandibular  nerve  and  enters  the  posterior  portion  of  the  ganglion. 

2.  The  motor  or  long  root,  which  is  formed  from  the  motor  fila- 
ments of  the  lingual  nerve  received  from  the  chorda  tympani  branch 
(A  the  facial. 

3.  The  sympathetic  root,  which  arises  from  the  sympathetic  plexus 
around  the  facial  artery. 


LOCAL  ANESTHESIA  UV^ 

The  l)raiuhcs  of  (lislril>Liti(jii  of  the  subnuixiUary  ^anj^hon  are  i^rin- 
cipally  those  that  siii)ply  the  suhmaxiUan'  nuico-sahvar>'  ghincl  and  its 
duct.  ()(lui-  branches  pass  upward,  and  interlace  witii  the  hn.uual 
ner\  e,  forming  a  ])lexus  on  the  side  of  the  tongue,  from  which  hlaments 
are  given  ofif  which  supj:)K'  the  mucous  membrane  of  the  mouth.  Bald- 
win and  other  anatcjmists  describe  a  sublingual  gangli(jn  which  is 
situated  on  the  branch  of  the  submaxillary  ganglion  which  passes  to 
the  lingual  nerve.  Occasionally  one  or  two  small  branches  are  found 
which  communicate  with  the  hyjxjglossal  nerve  (Meckel  and  Bose). 
None  of  the  branches  of  the  submaxillary  ganglion  are  distributed  to 
muscles,  which  is  in  marked  contrast  with  the  branches  from  the  otic 
ganglion. 

LOCAL  ANESTHESIA  OF  THE  TEETH,  SURROUNDING  TISSUE, 

AND  PARTS  OF  THE  FACE  PRESIDED   OVER  BY 

THE  TRIGEMINAL  NERVE. 

Local  anesthesia  may  be  obtained  by  several  methods:  by  direct 
application  of  the  drug  to  parts  such  as  the  mucous  membrane  of  the 
mouth  or  nasal  cavities,  by  hypodermic  injection  of  moderate  force, 
by  forcing  the  anesthetic  into  the  bone  under  high  pressure  causing 
infiltration  through  the  bone  cells,  and  by  the  conductive  or  blocking 
process.  It  should  be  borne  in  mind  that  no  injection  should  ever  be 
made  in  an  infected  area. 

The  ordinary  hypodermic  may  be  used,  but  where  a  deeper  anes- 
thesia is  required  it  is  necessary  to  inject  with  a  stronger  and  larger 
syringe  into  the  nerve  at  a  place  easy  of  access,  between  the  point  of 
operation  and  the  sensorium;  if  for  instance  it  was  desired  to  anesthetize 
the  lower  lip  "blocking"  could  be  done  at  the  mental  foramen  on  each 
side.  From  examination  of  various  mandibles  in  typical  skulls  it  will 
be  found  that  at  puberty  the  foramen  is  in  the  centre  of  the  body  of 
the  bone  at  a  perpendicular  line  between  the  two  premolar  teeth  (see 
Fig.  2) ;  by  studying  this  and  other  illustrations  as  well  as  specimens, 
one  can  judge  the  best  point  for  injection  within  the  vestibule  of  the 
mouth  for  this  particular  location.     Though   the  mental  foramen,  its 


164  THE  MOUTH 

canal  and  nerves  are  rather  constant  as  to  position  and  relation,  (see 
Fig.  3)  in  very  old  age,  if  the  mouth  be  edentulous,  the  mental 
foramen  is  often  found  nearer  the  top  of  the  body  of  the  mandible 
(see  Fig.  4) ;  there  may  be  also  modifying  pathological  conditions  mak- 
ing it  necessary  to  take  into  consideration,  not  only  age  but  the  many 
variations  that  are  discussed  in  the  general  text.  As  all  the  man- 
dibular teeth,  gum  tissue  and  most  of  the  mandible  are  presided  over 
b}'  the  mandibular  nerve,  the  anesthetizing  centre  for  this  region  would 
be  the  mandibular  foramen  which  is  one  of  the  most  constant  features 
in  anatomy. 

The  mandibular  foramen  is  in  the  median  surface  of  the  ramus 
generally  in  the  centre  and  placed  obliquely,  it  is  oval  in  shape  with  a 
sharp  border  of  bone  extending  upward  from  the  lower  margin  known 
as  the  lingula  to  which  is  attached  the  sphenomandibular  ligament. 

Above  the  foramen  is  a  depression  known  as  the  mandibular  sulcus, 
along  which  the  inferior  alveolar  nerves  and  vessels  pass  into  it.  In 
front  and  medial  to  these  is  the  lingual  nerve  (see  Fig.  130).  It  is  in 
the  region  of  the  sulcus  that  the  point  of  injection  should  be  carried 
for  anesthetizing  most  of  the  lower  jaw. 

The  blocking  of  the  nervous  system  is  more  complicated  in  the 
maxillary  region  than  in  the  mandibular  as  the  courses  of  distribution 
are  more  intricate,  for  this  reason  the  minute  knowledge  of  the  varia- 
tions in  the  anatomy  of  this  region  should  be  acquired  before  one  can 
intelligently  and  accurately  anesthetize  the  middle  portions  of  the 
face.  The  reflexes  of  the  various  ganglions  and  interlacing  of  the 
nerves  either  complicate  or  assist  in  proportion  to  the  operator's 
knowledge  of  the  distribution  of  this  nervous  system. 

If  the  maxillary  nerve,  as  it  passes  through  the  pterygoid  palatal 
fossse,  be  blocked  before  it  branches  to  the  sphenopalatine  ganglion, 
all  the  structures  in  front  of  this  region  would  be  deprived  of  sensation, 
this  might  not  be  desirable.  For  local  operation  upon  the  middle  face 
the  ordinary  points  of  injection  are  the  infraorbital  foramen,  the  inci- 
sive foramen,  the  greater  and  lesser  palatine  foramina,  and  the  alveolar 
foramina.  The  infraorbital  foramen  is  not  constant  in  position  as  it 
may  be  found  just  under  the  middle  of  the  infraorbital  ridge  or  it  may 


SVM  PATHETIC  GAXaiJ. I    CO.WKCTTI)   WITH    TRKHiM  I  \  AL   XKRVK     Km 

be  lateral  to  this  and  niiieh  lower  down,  the  location  ol  i)oint  of  injec- 
tion ran  usualK  he  detected  1)>'  careful  dii;ital  examination  in  the  ves- 
tibule of  the  mouth  going  upward  over  the  jDremolar  teeth. 

The  incisive  foramen,  a  funnel-shaped  opening,  is  situated  imme- 
diateh'  back  of  the  two  first  incisors.  It  is  in  the  interj^remaxillary 
suture  just  anterior  to  the  ])alatal  process  of  the  maxillary  bones,  four 
canals  usually  lead  into  it  from  the  nasal  cavities,  two  incisive  canals 
or  canals  of  Stenson,  for  the  accommodation  of  the  descending  palatine 
arteries,  and  two  canals  of  Scarpa,  anterior  and  posterior,  for  the  accom- 
modation of  the  nasopalatine  nerves.  This  foramen  is  the  most  easy 
of  access. 

The  greater  and  lesser  palatine  foramina  are  situated  near  the 
lateral  and  posterior  edge  of  the  hard  palate,  to  the  inside  of  the  third 
molar.  The  greater  palatine  foramen  is  the  outlet  to  the  pterygopalatal 
canal  and  conve^'s  the  anterior  palatine  nerve  which  passes  forward 
in  a  groo\c  in  the  hard  palate  to  the  incisive  foramen,  interlacing  with 
the  terminal  filament  of  the  nasopalatine  nerve.  The  two  lesser  palatine 
foramina  are  for  the  passage  of  the  middle  and  posterior  palatine  nerves. 

The  alveolar  foramina  are  much  more  difficult  to  reach  as  they  are 
not  constant  in  either  number  or  position,  it  is  for  this  reason  that  the 
same  result  is  not  always  obtainable  in  anesthetizing.  They  are  situated 
in  the  infratemporal  surface  of  the  maxilla  and  transmit  the  suj^erior 
alveolar  nerves  and  vessels.  The  best  point  for  injection  is  back 
of  the  tuberosity  along  the  posterior  wall  of  the  maxillan'  sinus; 
all  branches  of  these  nerves  should  l^e  blocked  as  they  preside  o\'er 
the  maxillary  molars,  premolars,  and  canine  teeth.  To  reach  the  maxil- 
lary incisors  the  injection  should  generally  be  made  in  the  infraorbital 
foramen. 


CHAPTER  VI. 
TEETH    INFLUENCED   BY   IRREGULAR   ERUPTION. 

RETARDED    ERUPTION    OR    IMPACTED    TEETH. 

Deformed,  impacted  and  misplaced  teeth  should  be  studied  not 
only  as  showing  evidences  of  diseased  conditions  in  themselves,  but 
they  must  be  regarded  as  symptoms  of  some  precedent  pathological 
disturbance  which  has  manifested  itself,  among  other  ways,  in  these 
anomalies.  One  must  know  the  history  of  the  development  and  growth 
of  the  face,  as  well  as  of  each  individual  tooth,  in  order  to  trace  the 
period  of  the  early  pathological  condition  which  caused  the  deformity. 
It  frequently  happens  that  at  the  same  time  other  facial  disturbances 
may  be  produced,  which  could  in  this  way  be  indicated  and  traced  by 
recognizing  the  relationship  between  the  causative  pathological  lesion 
and  its  various  manifestations. 

Precise  diagnosis  of  the  many  obscure  diseases  associated  with  the 
face  is  impossible  without  accurate  knowledge  of  the  anatomy  of 
the  head — even  to  each  individual  tooth.  This  knowledge  must 
include  the  various  characteristics  exhibited  by  the  anatomy  at  dif- 
ferent periods  of  life,  and  the  effect  of  early  pathological  conditions 
on  the  anatomy  of  the  teeth,  jaws  and  face  generally. 

Among  the  general  pathological  disturbances  which  bring  about 
deformity  or  retarded  eruptions  of  the  teeth  may  be  mentioned  syphilis, 
the  acute  exanthemata  such  as  scarlet  fever,  etc.,  and  disorders  of  nutri- 
tion. Among  local  causes  are  inflammations  of  the  jaw  bones  set  up 
by  carious  teeth  or  other  disturbances,  deformed  arches,  etc.  The 
growth  of  the  jaws  and  the  movement  of  the  teeth  is  in  a  forward 
direction,  consequently  anything  which  interferes  with  this  forward 
movement  will  cause  anomalous  eruption  and  impaction  of  the  teeth 
and  deformity  of  their  roots.     Chronic  conditions  resulting  from  any  of 


RETARDED  ERUPTIOX  OR  IMPACTED   TEETH  lt)7 

the  acute  exanthemata  nia>'  interfere  w  itli  the  ])roi)er  development  by 
causing  an  excessive  deposit  of  salts  of  calcium,  inducing  a  hyperplasia, 
which  may  either  he  general  or  localized  within  the  cancellated  bone. 

The  roots  of  misplaced  teeth  are  often  cur\ed  in  abnormal  shapes, 
or,  in  the  case  of  molar  teeth,  compressed  together.  They  are  not 
acti\'el\'  bent  into  these  positions,  but  are  built  or  formed  thus  in  the 
process  of  growth.  The>'  are  often  held  in  the  place  of  development, 
or  pushed  in  the  direction  of  the  leeist  resistance,  until  resorption  of 
the  bone  tissue  occurs,  when  they  usually'  make  their  appearance  in 
an  abnormal  position. 

The  increase  of  density  of  the  bone  not  only  prevents  the  teeth 
from  taking  their  normal  positions,  but  compresses  the  vessels  and 
nerves,  producing  local  malnutrition  and  general  discomfort,  not 
always  severe  enough  to  be  called  neuralgia,  although,  on  the  other 
hand,  this  disturbance  is  sometimes  so  severe  as  to  incapacitate  the 
individual  from  doing  any  kind  of  mental  work. 

Local  increase  in  the  density  (sclerosis)  of  the  bone  may  also  be 
brought  about  by  inflammation  of  the  periodental  membrane,  extend- 
ing into  the  alveolar  process.  Thus  the  cancellated  tissue,  instead  of 
being  spongy,  and  elastic,  becomes  hard  and  solid  (see  Fig.  45).  This 
condition,  following  caries  of  the  first  permanent  molar  soon  after  its 
eruption,  is  sometimes  a  cause  of  impaction  of  the  third  molar.  The 
severe  traumatism  to  the  jaw  may  cause  a  deposit  of  salts  of  calcium 
in  the  cancellated  tissue,  and  thus  bring  about  impaction.  A  heavy 
blow  on  the  chin  in  childhood  has  produced  ankylosis  of  the  man- 
dibular joint,  resulting  in  arrest  of  growth  of  the  jaw,  and  leaving 
insufficient  space  for  eruption  of  all  the  teeth.  Premature  extraction  of 
the  deciduous  teeth,  or  the  neglect  to  extract  them  at  the  proper  time, 
may  cause  malposition  of  the  permanent  teeth,  this  leading  in  turn 
to  impaction  of  unerupted  teeth.  Failure  to  freely  lance  the  gums  in 
retarded  eruption  of  the  deciduous  teeth  is  also  a  frequent  cause  of 
an  abnormal  density  in  the  cancellated  tissue  of  the  jaw. 

Impacted  teeth  may  be  present  without  giving  rise  to  an\'  local 
symptoms  whatever,  but  as  a  usual  thing  they  are  a  cause  of  many 
serious  local  and  often  far-reaching  general  disturbances. 


168 


TEETH  IXFLUEXCED  BY  IRREGULAR  ERUPTION 


]\Iagitot^  reports  man},'  cases  of  deformed  supernumerary,  misplaced, 
transposed  and  impacted  teeth  in  man,  monkey,  horse,  and  other 
animals.  These  are  fully  described  and  illustrated  in  the  pages  of  his 
valuable  and  important  work,  to  which  the  interested  reader  is  referred. 

Figs.  133  and  134  give  the  under  surface  of  a  monkey's  skull,- 
with  the  occluding  surface  of  the  mandible  showing  two  impacted  pre- 
molars in  the  roof  of  the  mouth  near  the  intermaxillary^  suture. 


Fig.  133  Fig.  134 

Figs.  133  and  134. — Monkey's  skull,  showing  two  impacted  maxillary  premolars. 

Figs.  135  and  136  are  from  an  x-ray  picture  of  the  same  skull,  show- 
ing the  impacted  teeth  and  their  roots,  also  the  developing  canines  in 
the  upper  jaw. 


'  Traite  des  Anomalies  du  Systeme  Dentaire,  Paris,  1877. 
2  F"rom  Dr.  Kirk's  collection. 


RETAI<ni:l)   l:l<LI'ri()\   OR   IMPACJ'JJ)    TJ-JJII 


169 


Local  Effects.  An  imi)a(tc'(l  tliiid  molar  ma\  press  a!L;ainsl  llie 
crown  of  the  srcond  molar  and  (Icnlal  caries  nia\'  be  indicated  in  this 
tooth,  or  itself  become  the  seat  of  caries  around  the  i)oint  ol  contact. 
Before  the  devitalization  of  pulp  severe  facial  neuralgia  may  occur. 
Again,  the  irritation  set  up  by  an  impacted  tooth  may  cause  a  conden- 
sation of  the  surroimding  l)one  with  j)ressure  on  the  mandibular  nerve 
and  its  branches  which   ramif\-  through   the  bone.     Failure  to  recog- 


FiG.  135  Fig.  136 

Figs.  135  and  136.— A'-ray  picture  of  the  same  as  shown  in  Fig.  133. 

nize  the  local  cause  may  lead  even  to  serious  and  dangerous  operations 
on  the  semilunar  ganglion.  No  case  of  facial  neuralgia  should  be 
operated  upon  without  search  for  a  possible  local  cause. 

Infection  from  a  pulp  devitalized  b\  an  impacted  tooth  in  the 
upper  jaw,  may  pass  up  into  the  maxillary  sinus  and  other  pneumatic 
spaces.     An  impacted  lower  third  molar,  in  its  attempt  to  erui:)t.  fre- 


170  TEETH  IXFLUEXCED  BY  IRREGULAR  ERUPTION 

quenth'  causes  a  cellulitis  which  extends  into  the  region  of  the  man- 
dibular joint,  causing  acute  ank^'losis.  It  may  also  set  up  tonsillitis, 
phar^^ngitis,  dysphagia  and  even  trismus,  if  suppuration  takes  place 
around  it.  Rarely,  infection  may  extend  from  the  dental  and  maxil- 
lary veins,  through  the  pter^-goid  plexus  to  the  cavernous  sinus. 

General  Effects. — It  has  been  well  established  that  impacted  teeth 
and  the  antecedent  pathological  condition  of  the  bone  may  be  a  source 
of  great  disturbance  of  the  whole  nervous  system.  Cases  can  be  cited 
of  serious  disturbances  of  the  nervous  system  being  cured  by  the 
removal  of  impacted  teeth  and  also  by  the  removal  of  hard  bone  which 
has  become  consolidated  by  an  excessive  deposit  of  salts  of  calcium 
within  the  spongy  or  cancellated  tissue. 

Diagnosis. — The  diagnosis  by  superficial  observation  of  many  of 
these  conditions  of  the  mouth,  and  even  of-  the  internal  structure  of 
the  face,  is  comparatively  easy.  The  general  character  of  the  erupted 
portion  of  a  tooth,  its  position,  and  the  firmness  with  which  it  is  held  in 
the  alveolar  process,  can  be  studied  with  the  aid  of  a  mouth  mirror 
and  a  few  dental  instruments,  provided  that  the  surgeon  has  a  minute 
knowledge  of  both  the  typical  and  abnormal  anatomy  of  this  region. 
The  same  qualification  is  demanded  in  using  the  x-rays  for  diagnosis 
of  the  more  obscure  diseases.  No  matter  how  good  a  skiagraph  be 
obtained  it  is  useless  unless  the  reader  can  distinguish  the  pathological 
from  the  normal  condition,  w^hich  demands  that  he  must  know^  the 
many  deviations  from  typical  anatomy  that  even  a  normal  condition 
can  present. 

Value  of  X-ray  Pictures. — The  x-rays  are  of  inestimable  value 
when  used  in  conjunction  with  other  means  in  the  diagnosis  of  the 
more  obscure  abnormalities  of  the  teeth.  There  are  many  times,  in 
fact,  w^hen  an  intelligent  interpretation  of  the  case  would  be  impos- 
sible without  the  use  of  x-rays  in  locating  the  abnormal  or  diseased 
condition.  Instances  could  be  cited  of  patients  suffering  from  severe 
neuralgia  who  had  been  treated,  without  success,  with  opiates  and 
other  drugs,  because  no  local  cause  had  been  suspected,  or  in  whom 
the  symptoms  had  been  ascribed  to  remote  causes,  when  the  skiagraph 
revealed  an  impacted  tooth,  the  removal  of  which  brought  about  imme- 
diate and  permanent  relief. 


RETARDED  ERLPTIOX  OR  IMPACTED   TEETH  171 

In  the  case  of  llie  lower  lliinl  molar  the  (iiieslion  of  the  ad\  isability 
of  removing-  tlu-  inipaeted  toolh  or  the  one  next  to  it,  is  often  settled 
by  a  good  .v-ra\  picture;  thus,  where  the  .r-ray  shows  that  the  adjacent 
tooth  has  been  damaged  and  that  the  impacted  tooth  could  easily 
erupt  to  take  its  place,  extraction  of  the  former  would  be  indicated 
and  only  one  tooth  sacrificed  instead  of  two. 

Fig.  137^  gives  a  general  idea  of  the  arrangement  and  position  of 
the  deciduous  and  permanent  teeth,  and  of  their  relations,  about  the 


Fig.   137. — Skull  of  a  child,  aged  about  six  years,  showing  all  the  deciduous  teeth  in  position  and 

the  developing  permanent  teeth. 

sixth  or  seventh  year.  The  external  walls  of  the  alveolar  process  of 
the  upper  and  lower  jaws  have  been  removed,  together  with  some 
of  the  cancellated  tissue,  exposing  the  roots  of  the  deciduous  teeth 
and  the  crowns  of  the  permanent  ones.  It  will  be  noticed  that  at 
this  age  nearly  all  of  the  space  of  the  maxillary  bone  is  occupied  by 
the  dental  organs,  there  being  but  little  room  for  the  maxillary  sinus. 
It  would  seem  clear,  that  by  interference  with  the  natural  processes 

^  For  further  description  of  this  illustration,  see  Fig.  107,  of  which  it  is  a  repetition. 


172 


TEETH  IXFLUEXCED  BY  IRREGULAR  ERUPTION 


at  this  period  of  life,  the  permanent  teeth  can  be  deflected  or  detained 
from  assuming  their  normal  positions,  thus  modifying  the  shapes  of 
the  maxillary  sinus  or  nasal  cavities.  When  these  chambers  are  changed 
in  form,  size,  or  position,  associated  cavities  and  adjoining  structures 
will  also  be  changed.  The  shape  of  the  orbit  may  also  be  modified  to 
such  an  extent  that  the  eye  may  be  affected,  making  it  myopic  or 
hypermetropic.  In  this  figure  the  crown  of  the  upper  first  molar  is 
visible.  The  position  of  the  germs  of  the  second  and  third  molars 
is  higher  up  and  further  back,  therefore  they  must  be  close   to   the 


Fig.   138. — Side  view  of  the  upper  and  lower  jaws  of  a  child  about  seven  or  eight  years  of  age,  showing 
the  deciduous  teeth,  the  first  molars,  and  the  germs  of  other  permanent  teeth. 


under  surface  and  posterior  portion  of  the  orbit.  This  was  interest- 
ingly demonstrated  by  a  patient  referred  to  the  Department  of 
Dentistry  of  the  University  of  Pennsylvania,  who  had  an  impacted 
upper  third  molar,  the  crown  of  which  was  in  the  upper  portion  of 
the  posterior  wall  of  the  maxillary  sinus.      (See  Fig.  142.) 

Fig.  138  is  from  a  specimen  of  the  upper  and  lower  jaws  of  a  child 
about  seven  or  eight  years  of  age.  All  the  deciduous  teeth  are  in 
position  except  the  incisors.  The  first  molars  have  erupted,  the  other 
permanent  teeth  are  in  fairly  normal  position  for  this  age. 


SUPERNUMEK.  I  AM '    TI.I.TII 


173 


F'ig.  139  is  from  a  similar  jjrcparat ion  ol  a  child  about  IwcKe  or 
thirteen  years  of  age.  It  will  be  noticed  that  the  position  of  the  roots 
of  the  ui)i)er  hrst  and  second  premolars  and  the  roots  ol  the  first 
molar  ha\e  been  interfered  with  1)\   some  ])atholoi!,ieal  condition. 


Fig.   139.— Side  view  of  upper  and  lower  jaws  of  a  child  about  twelve  or  thirteen  years  of  age. 


SUPERNUMERARY    TEETH. 

The  development  of  a  supernumerary  tooth  or  teeth  may  also 
cause  impaction  of  a  normal  tooth.  Two  marked  cases  have  come 
under  the  writer's  observation,  the  first  in  a  skull  belonging  to  Dr. 
Kirk's  collection,  where  thirteen  small  supernumerary  teeth  are  devel- 
oped in  the  position  of  the  root  of  the  left  upper  first  incisor,  which 
was  found,  upon  dissection,  to  be  impacted  between  the  floor  t.f  the 
nose  and  the  roof  of  the  mouth.  The  other  case  was  in  the  mouth  of 
a  patient  of  Dr.  Huey's,  of  Philadelphia,  where  thirty-five  small  super- 
numerary teeth  were  found  within  the  alveolar  process,  in  the  space 
which  should  have  held  the  left  central  incisor.  After  removing  the 
supernumerary  teeth,  the  permanent  normal  incisor  could  be  seen 
resting  between  the  plates  of  bone  forming  the  roof  of  the  mouth  and 
the  floor  of  the  nose. 


174 


TEETH  IXFLUEXCED  BY  IRREGULAR  ERUPTION 


Fig.  140  is  a  photograph  from  a  skull  in  Dr.  Kirk's  collection. 
It  affords  also  a  good  idea  of  the  general  condition  found  in  the  mouth 
of  Dr.  Huey's  patient.  The  permanent  first  incisor  was  not  removed 
when  the  supernumerary  teeth  were  extracted,  as  Dr.  Huey  and  the 
writer  had  some  hopes  that  it  would  assume  its  normal  place  with  the 
other  teeth.  Six  months  after  the  operation  the  tooth  had  advanced 
more  than  half  its  length,  and  eighteen  months  later  it  descended  into 
its  normal  position. 


Fig.   140. — An  odontoma  and  an  impacted  first  incisor. 

Fig.  141  is  an  illustration  of  the  first  incisor  and  supernumerary 
teeth  taken  from  the  skull  shown  in  Fig.  140. 

Fig.  142  is  an  illustration  made  from  a  section  giving  an  idea  of  the 
position  of  the  tooth  in  this  patient's  mouth.  If  this  crown,  as  shown  in 
the  illustration,  had  roots  of  normal  length,  they  would  extend  back  across 
the  sphenomaxillary  space,  the  points  of  the  roots  would  be  near  the 
sphenoidal  sinus,  and  the  roots  would  more  than  likely  be  covered  by  a 
thin  lamina  of  bone  developed  from  the  original  tooth  sack  or  capsule  of 
the  maxilla.  In  cases  where  teeth  have  been  found  impacted  in  the  upper 
part  of  the  maxilki,  similar  to  that  shown  in  this  illustration,  they  are 


Si'PKRSUMER.  I  RY   TKETII 


17.") 


coiiiiiionU  spoken  of  as  lui\  ing  passed  upward.  'Hiis,  in  the  oi;inion  of 
the  writer,  is  incorrect.  It  is  more  likely  that  many  (^f  the  teeth  so 
found  inii)acte(l  ha\ c  ne\  er  passed  down  from  their  place  of  develop- 


» 


//*! 


Fig.   141. — \'ic\vs  of  iIk-  imi);u-lc'(l  looih  and  odontoma  removed  from  the  jaw  illustrated  in  Fig.  140. 

ment.  In  this  particular  case,  through  some  inflammatory  process, 
the  tooth  and  its  capsule  became  adherent  to  the  posterior  wall  of  the 
maxilla,   the  intrinsic  force  being  insufficient  to  force  the  tooth  into 


--  ^                                              Fig.   143. — A  first  and  second  incisor,  and 

Fig.   142. — .An  illustration  representing  an        a    canine   tooth    removed    from    the   maxillary 

impacted   tooth    in  the    posterior    wall   of    the         sinus  of  a  patient  who  had  been  suffering  with 

maxillary  sinus.  neuralgia. 

proi)er  position  at  the  time  it  shcnild  ha\e  made  its  descent.  It  is  some- 
what analogous  to  an  adherent  testicle  in  the  abdominal  cavity  or  in 
the  inguinal  canal.     There  is  no  more  reason  to  think  that  the  tooth 


176 


TEETH  IX  FLU  EX  LED  BY  IRREGULAR  ERUPTIOX 


passes  upward  than  that  the  testicle  passes  up  from  the  scrotum  into 
the  inguinal  canal  or  abdominal  cavitv. 


i% 


Fig.   144. — An  impacted  canine  tooth  with  the  apex  of  the  root  within  the  nasal  cavity. 


Apex  of  an  impacted  tooth 


Fig.   145. — E.xternal  wall  of  the  nasal  cavity,  seen  from  the  inside,  showing  the  apex  of  the  impacted 

canine  tooth  illustrated  in  Fig.  144. 


SUPERNUMl'.KARV   TEIJII  177 

Fx*^.  143  ivprcstMils  three  inii)ac-lt'<l  pcnnaiuMit  leelh,  lirst  and  second 
incisor,  and  canine,  whicli  were  ix-nioxed  from  a  lixint;  i)alient  suffering 
from  neuralgia  and  sinusitis. 

Fig.  144  is  taken  from  a  specimen  which  belonged  to  i'rotessor 
James  Truman's  collection.  It  shows  an  impacted  right  canine,  the 
external  bone  has  been  cut  away,  exposing  the  tcjoth  and  its  root. 
The  tooth  is  a  little  below  the  place  of  development.  The  apex  is 
curved  forward  and  inward,  the  inward  i)ortion  passing  just  into  the 
nasal  cavity  eis  shown  in  Fig.  145.  A  little  external  to  the  apex  of  the 
root  is  an  opening  into  the  maxillary  sinus. 


Fig.   146. — Two  impacted  canine  teeth.    Their  malposition  caused  the  loss  of  the  left  first  and  second 
premolars,  also  the  loss  of  the  right  first  premolar. 

Fig.  145  is  a  view  from  the  other  side  of  the  specimen  seen  in  Fig. 
144,  showing  the  apex  of  the  impacted  canine  in  the  external  wall  of 
the  nasal  cavity. 

See  Fig.  178  for  impacted  canine  with  crown  immediately  over  the 
socket  of  the  right  first  incisor,  the  root  passing  upward  and  backward. 

Fig.  146  shows  two  canines  impacted  in  the  upper  jaw,  lying  at 
nearly  right  angles  to  each  other.  They  were  entirely  covered  with 
bone,  and  were  exposed  by  a  surgical  bur.  The  end  of  the  root  of  the 
right  canine  is  somewhat  curved.  There  is  only  a  slight  layer  of  bone 
between  it  and  the  floor  of  the  sinus.  The  la>er  of  bone  is  perforated 
12 


178 


TEETH  IXFLUENCED  BY  IRREGULAR  ERUPTION 


by  three  small  openings.     This  malposition  caused  the  loss  of  the  left 
first  and  second  premolars,  also  of  the  right  first  premolar. 


(«s^«^*-^-^^'-^*^|k^  ( 


Fig.   1-1:7. — Showing  two  inverted  canine  teeth. 


-Root  of  canine  tooth 
Crown  of  canine  tooth 


Fig.   148. — An  impacted  canine  tooth,  the  crown  in  the  roof  of  the  mouth,  the  greater  portion  of  the 

root  in  the  maxillary  sinus. 

Fig.  1471  shows  two  inverted  canine  teeth  in  the  inner  and  lower 
border  of  the  orbital  margin.  This  class  of  impaction  would  interfere 
with  the  function  of  the  nasolacrimal  duct. 

1  This  picture  was  presented  by  Dr.  John  Gravers'  University  of  Utrecht,  Holland. 


SUPERX L MKK. \I<Y   TKIJII 


179 


Fig.  14S  is  a  iKJstcrior  \icw  of  a  transverse  vertical  section  of  a 
face,  made  in  the  region  oi  the  In'st  premolar  teeth.  Besides  other 
interesting  i)oints,  the  crown  of  the  canine  tooth  has  penetrated  the 
palatal  surface  of  the  mouth  and  the  root  is  within  the  anterior  portion 
of  the  sinus.  Before  the  dissection  was  made,  the  root  was  covered 
with  a  thin  lamina  of  bone.  Similar  conditions  are  often  found,  involv- 
ing not  onl\'  the  canine  t(joth.  but  also  the  third  molar,  and  occasion- 


FiG.   149. — An  .v-ray,  showing  impacted  right  canine. 

ally  other  teeth,  which  often  remain  in  such  positions  for  years 
without  giving  any  trouble  until  after  middle  life,  when  by  natural 
resorption  of  the  bone  the  crown  and  root  become  exposed  within  the 
maxillar\-  sinus  or  nasal  ca\it\-.  at  which  time  they  may  cause  some 
disturbance. 

Fig.   149  is  an  .v-ra\-  picture  giving  anterior  view  of  a  dried  skull. 
It  shows  an   impacted   canine   tooth   with   the  crown   resting  against 


180 


TEETH  IXFLUEXCED  BY  IRREGULAR  ERUPTION 


the  roots  of  the  first  and  second  incisor  teeth.  The  roots  of  the  first 
molar  appear  to  be  within  the  maxihary  sinus,  although  they  are  in 
normal  position.  This  impression  is  produced  by  the  thinness  of  the 
lateral  walls  of  the  sinuses  which  only  slightly  resist  the  passage  of  the 
.v-ravs.     When  a  canine  tooth  is  in  this  position  it  should  be  extracted, 


Fig.  150. — X-ray  showing  an  inverted  maxillary  third  molar.    (A'-ray  by  Dr.  Pancoast.) 

as  it  would  probably  cause  devitalization  of  one  or  both  of  the  incisors, 
and  should  the  pulp  become  infected,  the  disease  might  extend  to  the 
maxillary  sinus.  Teeth  in  this  position  often  cause  serious  systemic 
trouble. 

Fig.    150  shows   the  occluding  surface   of   the   upper   third   molar 
pointing  upward  toward  the  posterior  portion  of  the  orbit.    The  patient 


sLri':R.\LMj:R. irv  i eijii 


IM 


had  been  sufiferini>  from  (HsUirl)eince  (;f  the  left  e>e  for  a  long  time. 
Considerable  improvement  t(jok  place  in  the  eye  soon  after  the  extrac- 
tion of  the  inverted  tooth. 


»  -V- 


'^^' 


Fig.   151. — An    impacted  first  incisor,  with  the 
crown  partly  in  the  incisive  foramen. 


Fig.   152. — An  impacted  supernumerary 
tooth. 


Fig.   153. — An  impacted  maxillary  third  molar.     A  similar  condition  is  found  on  the  opposite  side 

of  the  skull. 

Fig.  151  illustrates  an  impacted  left  first  incisor,  which  lies  diagon- 
ally across  the  alveolar  process,  with  the  apex  of  the  root  near  the 


182 


TEETH  IXFLUEXCED  BY  IRREGULAR  ERUPTION 


outer  side  of  the  left  anterior  nares.  The  crown  passes  across  the 
incisive  foramen.  Impaction  of  this  kind  would  more  than  likely 
interfere  with  the  true  function  of  the  nerves  and  vessels  passing  through 
this  foramen. 

Fig.  152  illustrates  a  supernumerary  second  incisor  impacted  imme- 
diately below  the  floor  of  the  nose.  There  was  no  enlargement  of  the 
external  plates  of  the  incisive  fossa,  the  floor  of  the  nose,  or  the  roof  of 
the  mouth.  The  tooth  was  accidentally'  discovered  when  cutting  the 
bone  transversely. 


Fig.  154. — From  a  Philippine  skull,  showing  an  impacted  maxillar}^  third  molar. 


Fig.  153  exhibits  an  impacted  and  misplaced  third  molar.  The 
occluding  surface  of  the  molar  was  even  with  the  external  plate  of  the 
alveolar  process,  the  roots  being  compressed  and  somewhat  shorter 
than  normal.  A  complete  thin  layer  of  bone  made  a  conical-shaped 
partition  between  the  tooth  sockets  and  the  sinus.  A  similar  condi- 
tion existed  on  the  opposite  side  of  the  jaw. 


SUPERXUMER.  \Ry   TEE  III 


183 


Fig.  154. — Matlc  from  ihc  right  side  of  a  Philippine  skull  in  Dr. 
Ketcham's  collection.  It  shows  a  similar  condition  of  inii)action  of 
the  maxillary  third  molar  (o  that  in  the  Caucasian  skull,  Fig.  153. 


Fio.  155. — Is  from  the  left  side  of  the  same  skull  as  shown  in  Fig.  154. 


1  i^ 


\    1 


rfi«»sas^;. 


# 


/ 


Fr;.   156. — An  impacted  mandibular  third  molar. 

Fig.  156  exhibits  an  impacted  mandibular  third  molar  in  the  ramus 
of  the  jaw  just  below  the  anterior  portion  of  the  mandilular  notch,  the 
tooth  being  inverted.    In  this  case  the  capsule  of  the  germ  of  the  tooth 


184 


TEETH  IXFLUEXCED  BY  IRREGULAR  ERUPTION 


became  adherent  to  the  walls  of  the  jaw,  and  lost  its  position  within 
the  forming  cancellated  tissue,  when  the  body  of  the  jaw  grew  down- 
ward and  forward. 

Fig.  157  shows  a  molar  tooth  in  the  ramus  of  the  mandible.  There 
is  a  light  area  around  the  greater  portion  of  the  crown.  Teeth  in  this 
position  in  the  living  subject  often  give  considerable  trouble  and  their 
existence  is  very  difficult  to  diagnose  without  the  use  of  x-rays. 

Fig.  158  illustrates  the  most  common  kind  of  impacted  lower  third 
molar  teeth.  They  often  give  great  trouble  by  irritating  the  inferior 
alveolar  nerve.     They   may   also  cause  an  inflammatory  condition  in 


Fig.  157. — A'-ray  showing  misplaced  mandibular  third  molar.     (Kirk.) 

this  region,  and  the  cellulitis  may  extend  to  the  mandibular  articulation 
and  the  base  of  the  tongue. 

Figs.  159  and  160  represent  a  similar  impaction.  In  Fig.  160  the 
external  portion  of  the  bone  covering  the  tooth  has  been  removed,  and 
in  Fig.  159  the  internal  jDortion.  In  both  cases  it  will  be  observed  that 
the  mandibular  canal  is  encroached  upon.  It  is  often  necessary  to 
cut  away  a  portion  of  the  bone  with  the  surgical  engine  before  a  tooth 
so  situated  can  be  removed. 

Figs.  161  and  162  give  two  views  of  an  impacted  third  molar.  In 
Fig.  161  the  tooth  is  in  jxjsition  as  discovered  when  the  cap  of  bone  was 
removed;  in  F'ig.  162  the  tooth  is  removed  from  its  socket,  showing  its 
inner  surface.     Its  crypt  is  aKso  seen.     The  second  molar  is  a  pulpless 


S UPERN UMER. [RV   7 KE 1 II 


ISo 


Fig.   158. — A  common  form  of  impacted  lower  third  molars. 


Fig.  159 


Fig.   160 


186 


TEETH  IXFLUEXCED  BY  IRREGULAR  ERUPTION 


tooth,  the  posterior  root  of  which  shows  where  the  impacted  tooth  has 
pressed  against  it,  causing  resorption  of  a  portion  of  the  root  until  the 


Fig.  161 


Fig.  162 
Figs.   161  and  162.— Two  views  of  an  impacted  lower  third  molar.     Uppsr  figure  shows  tooth 
in  position;  in  lower  figure  the  tooth  is  removed  from  its  pocket.     Part  of  the  posterior  root  of  the 
second  molar  has  been  resorbed,  exposing  the  root-canal,  more  than  likely  causing  the  devitaliz- 
ation of  the  tooth  and  thus  producing  neuralgia,  induced  by  the  pressure  from  the  impacted  tooth. 

pulp-canal  was  fully  exposed.     The  enamel  of  the  impacted  tooth  is 
somewhat  lost  by  friction  against  the  second  molar.     The  roots  of  the 


SUPERNUMEK. \I<V   TEITII 


187 


impacted  teeth  ha\c  a  sli.uht  curve  inward  at  their  i)()ints;  the  con- 
ciivity  fits  immediately  o\er  the  alveolar  or  mandibular  nerve,  and 
has  probabh'  caused  i)ain  !)>•  pressure.     The  terminations  of  I  lie  roots 


Fu;.   163. — A'-ray  picture,  showing  an  impacted  second  mandibular  premolar  tooth. 

(.Y-ray  by  Dr.  Pfahler.) 


Fig.   164. — Showing  the  resorption  of  the  roots  of  the  first  mandibular  molar  (Fig.  163),  where  the 
crown  of  the  second  premolar  had  pressed  against  the  roots. 

are  not  fully  formed,  the  apical  openings  being  large;  it  will  also  be 
noticed  that  the  roots  of  the  teeth  in  the  jaw  are  longer  than  usual, 
that  of  the  canine,  for  example,  passing  below  the  alveolar  or  man- 
dibuar  nerve. 


188 


TEETH  IXFLUEXCED  BY  IRREGULAR  ERUPTION 


Fig.  163,  from  an  .v-ray  picture,  showing  an  impacted  second  right 
mandibular  premolar,  its  crown  is  resting  against  the  roots  of  the  first 


Fig.  165 


Fig.  166 

Figs.   165  and  166. — Two  views  of  an  impacted  mandibular  third  molar.     In  Fig.  165  it  is  in  its 

abnormal  position;  in  Fig.  166  it  is  taken  from  its  crypt. 


SiPERX L  MRR. [RV   TEETH 


189 


molar  and  lias  caused  resoriitioii  of  llie  ends  ot   the  roots  as  shown  in 
the  extracted  tooth  (Fii;.  164). 

Figs.  165  and  166  represent  another  imjiacted  third  molar,  situated 
on  the  inner  side  of  the  jaw  and  i)ointing  slightly  downward.  The 
posterior  root  of  the  second  molar  is  slightly  resorhed.  rp(^n  uncover- 
ing the  tooth  and  taking  it  from  its  cr\i)t,  it  was  foimd  to  be  incased 
in  a  thin  shell  of  bone,  as  though  the  dental  capsule  had  (jssihed  sejia- 
rateh-  around  the  tooth.  The  inner  portion  of  the  shell  is  still  in  i)osi- 
tion.   the   nerve  and   its  accomiKuning   tissues  are  seen   passing   into 


Fig.  167. — An  impacted  mandibular  third  molar,  and  a  mandibular  third  molar  with  curved 
and  thickened  root,  both  belonging  to  the  same  jaw.  The  bone  is  much  more  compacted  than 
normal  bone. 


the  mandibular  foramen  and  immediately  under  or  against  the  shell. 
Here,  again,  must  ha\e  been  an  obscure  cause  of  neuralgia. 

Figs.  167  and  168  illustrate  the  right  and  left  halves  of  the  lower 
jaw,  Fig.  167  showing  the  internal  surface  of  the  right  half,  while 
Fig.  168  shows  the  external  surface  of  the  left  half.  In  the  former  we 
find  the  roots  of  the  third  molar  curved  backward  at  almost  a  right 
angle,  and  enlarged  by  an  abnormal  deposit  of  cementum  until  the 
independent  character  of  the  roots  is  lost,  the  two  being  fused  together. 

Fig.    168   shows   an   impacted   tooth    pushing   directly   against   the 


190 


TEETH  IXFLUENCED  BY  IRREGULAR  ERUPTION 


tooth  in  front  of  it.  The  roots  of  this  tooth  have  also  become  much 
enlarged  by  deposit  of  cementum,  while  the  surrounding  bone  has 
thickened  and  grown  more  compact. 


^../ 


Fig.  168. — An  impacted  mandibular  third  molar,  and  a  mandibular  third  molar  with  curved 
and  thickened  root,  both  belonging  to  the  same  jaw.  The  bone  is  much  more  compact  than 
normal  bone. 


Fig.   169. — A  mandible  showing  an  iiucrlcfl  lower  third  molar  erupting  into  the  right  submaxillary 

fossa.      (Ur.  Whitney.) 


SUPERNUMER.  I  A'  J'   TEETH  191 

Fig.  169  gives  an  illustration  where  the  mandibular  third  molar 
has  become  inverted  and  is  erui)ling  into  the  submaxillar>'  fossa. 

Fig.  170'  is  from  an  .v-ray  picture  showing  impaction  of  the  second 
and  third  right  mandibular  molars,  it  is  possible  that  the  third  is 
between  the  first  and  second  molars. 


Fig.   170. — An  A'-ray  picture  of  a  patient  of  Dr.  A.  R.  Cook,  of  Syracuse,  X.  V.,  it  shows  impacted 

second  and  third  mandibular  molars. 

Extraction. — It  would  ha\'e  been  almost  impossible  to  extract 
either  of  the  two  last-named  third  molars  without  fracturing  the  jaw, 
unless  the  solid  bone  over  the  roots  of  the  teeth  had  been  removed 
first.  In  a  case  of  this  kind,  it  is  much  better  to  use  the 
surgical  engine  bur  than   to  cut  or  break   the  parts  awa>'  with  chisel 

'  From  a  patient  of  Dr.  .A.  R.  Cook,  Syracuse,  X.  V. 


192  TEETH  IXFLUEXCED  BY  IRREGULAR  ERUPTION 

or  forceps.  A  fracture  at  this  point  will  cause  serious  results;  the 
mylohyoid  artery  is  liable  to  be  lacerated  or  even  severed,  and  the 
hemorrhage  is  difficult  to  control.  It  is  not  easy  to  keep  the  region 
clean  or  aseptic,  and  the  consequent  inflammation  will  often  interfere 
with  free  movement  of  the  jaws  in  deglutition,  speech,  etc.  The  glottis 
even  may  become  closed. 

Diagnosis. — Impacted  teeth  are  frequently  the  obscure  or  hidden 
cause  of  various  diseases  about  the  mouth  and  jaws.  There  is  often 
no  external  evidence  of  their  impaction;  patients  ma}^  even  claim  that 
the  teeth  which  cannot  be  seen  have  been  extracted. 

Impacted  incisors  are  liable  to  induce  diseases  of  the  nose  or  to 
produce  neuralgia  by  the  tooth  pressing  the  sphenopalatine  nerve  as 
it  passes  through  the  incisive  foramen.  Occasionally  they  cause  a  par- 
tial separation  between  the  septum  and  the  nasal  floor.  Impacted 
teeth  may  become  either  partly  lodged  in  the  inferior  meatus,  some- 
times causing  the  closure  of  the  lower  portion  of  the  nasolacrimal 
duct,  or  they  may  lie  horizontally  across  the  roots  of  the  incisors,  espe- 
cially of  the  second,  or  the  roots  of  the  premolars,  causing  the  devi- 
talization of  these  teeth.  Impacted  upper  third  molars  are  liable  to 
interfere  with  the  nerves  and  vessels  in  the  floor  of  the  maxillary 
sinus,  near  where  they  pass  through  the  superior  alveolar  foramina  into 
the  sinus.  They  may  also  cause  an  enlargement  of  the  tuberosity 
outwardly  until  it  interferes  with  the  ramus  of  the  lower  jaw,  and 
produces  a  cellulitis  which  may  extend  to  the  mandibular  articulation, 
causing  false  ankylosis. 

Neuralgia. — The  three  impacted  teeth  shown  in  Fig.  143  caused 
a  baffling  case  of  facial  neuralgia  until  they  were  found  and  removed. 
The  patient  was  past  middle  life  and  had  suffered  from  neuralgia.  He 
had  no  teeth  in  the  alveolar  process  of  the  right  maxilla,  the  region  of 
pain,  almost  all  of  them  having  been  extracted  in  the  hope  of  giving 
relief.  The  sinus  was  opened  by  the  late  Professor  Garretson  and 
the  writer  in  search  of  the  cause.  It  was  somewhat  surprising  to  see 
three  crowns  i)rotruding  into  the  sinus,  the  roots  being  imbedded  in  the 
inner  anterior  angle  of  the  wall  of  the  maxillary  sinus.  After  the  teeth 
were  extracted  by  small  forceps  the  parts  were  treated  in  the  usual 


SUPERX I  MEK.  1  A'  1  ■    //■./•.  Til  1 03 

\va\-,  willi  relict  iiiul  su1)sl'(iik'1iI  cure.  V\\v  (.rtnvns  were  in  normal 
shape  and  (luite  hcalth\-,  the  roots  more  or  less  clefertive.  The  i)ul|)s 
were  alixc.  and  il  is  |)i()l)al»le  thai  the  nerxes  were  impini^ed  njxin  at  the 
points  of  the  roots,  thus  causing  the  pain.  The  writer  has  seen  several 
cases  where  a  greater  ]X)rtion  of  the  root  of  a  single  tr)oth  was  foimd 
within  the  antrum,  hut  he  beliexcs  this  to  be  the  oiiK  case  where 
three  such  teeth  have  been  reported.  In  the  lower  jaw  imi)acled  leeth 
ai-e  liable  to  impinge  upon  the  mandibular  ner\e,  thus  becoming  a 
hidden  cause  of  neuralgia  in  this  region,  which  ma\-  have  its  s>'mp- 
toms  exhibited  almost  anywhere  along  the  distribution  of  the  nerves, 
eventualh'  producing  neuritis  that  may  pass  back  along  the  nerve 
e\en   into  the   brain. 

Cysts. — Teeth  prevented  from  i:)assing  in  their  normal  course  may, 
through  the  resorption  of  the  bone,  ad\ance  in  almost  any  direction  and 
be  erupted  through  the -bone  even  upon  its  cervical  aspect.  Impacted 
or  supernumerary  teeth  may  also  i)roduce  dentigerous  cysts  of  various 
sizes  and  forms,  some  of  which  may  cause  the  cortical  portion  of  the 
bone  to  be  pushed  outward  until  large  disfiguring  tumors  are  formed. 
These  have  sometimes  been  mistaken  for  malignant  growths,  and  the 
entire  body  of  the  jaw  has  been  removed  on  account  of  this  enlarge- 
ment and  mistaken  diagnosis. 

There  is  considerable  confusion  in  the  nomenclature  of  tumors 
arising  from  the  dental  follicle.  A  dental  cyst  is  understood  by  the 
writer  to  be  one  originating  from  remains  of  the  embryonic  epithelial 
elements  of  the  peridental  membrane.  These  epithelial  "rests,"  as  a 
result  of  septic  infection  of  the  tissue,  rapidly  proliferate,  the  central 
portions  degenerate,  and  ultimately  liquefy,  thus  giving  origin  to  the 
cx'stic  fluid.  A  dental  cyst  is  lined  with  cortical  epithelium,  which 
in  some  instances  may  become  ciliated.  A  dentigerous  cyst  is  under- 
stood to  be  a  growth  brought  about  by  tissue  changes  occurring  in  the 
dental  capsule  during  developmental  periods;  as  the  name  implies, 
it  contains  one  or  more  teeth. 

The  .v-rays  are  the  most  valuable  means  of  diagnosis.  In  both  cases 
the  principles  of  treatment  are  the  same.  This  consists  of  evacuation 
of  the  fluid  and  solid  contents  of  the  cyst,  and  comj^lete  removal  of 

13 


194 


TEETH  IXFLUEXCED  BY  IRREGULAR  ERUPTION 


the  c^st  wall,  which,  as  already  noted,  partially  or  entirely  is  lined 
with  epithelial  cells.  If  the  cyst  wall  be  not  completely  removed,  these 
epithelial  cells  will  continue  to  secrete  fluid,  and  may  proliferate  with 
possibl}'  the  development  of  a  malignant  growth.  The  great  majority 
of  dental  and  dentigerous  cysts  can  be  removed  through  the  mouth, 


Fig.  171. — A'-ray  picture  from  a  child  aged  nine  years,  showing  a  retained  deciduous  second  molar 
surrounded  by  an  ovoid  clear  area  which  probably  partook  the  nature  of  a  follicular  odontome. 


without  operations  on  the  face,  and  without  destroying  the  continuity 
of  the  jaw  bone,  in  case  of  involvement  of  the  mandible. 

Fig.  171  is  an  x-ray  photograph  from  the  jaw  of  a  child  aged  nine 
years.  It  shows  a  retained  deciduous  second  molar  at  the  bottom  of 
the  jaw,  surrounded  by  an  ovoid  clear  area.    This  patient  had  a  swell- 


SUPERXUMERARY  TEETH  195 

ini^  of  the  left  side  of  the  knver  jaw  for  about  two  \ears,  which  grad- 
ualK   increased  in  size,  causing  consideral)le  deformity. 

Examination  showed  a  smooth  swelling  about  the  size  oi  a  hen's 
egg,  witli  thill,  i)archment-lik:e  walls,  covered  only  b\-  the  mucous 
membrane.  A  diagnosis  of  dentigerous  cyst  was  made.  At  operation 
through  the  mouth  the  thin  shell  of  bone  was  found  to  contain  no 
fluid,  but  a  resilient  mass  of  pinkish-white  tissue  surrounded  by  a  sac 
of  darker  color.  The  contents  including  the  soft  tissue,  the  dental 
sac,  and  the  tooth  shown  in  the  picture  were  removed  and  the  cavity 
lightly  packed  with  gauze.    The  patient  made  an  une\'entful  recovery. 

Pathological  Report. — Characteristics  of  Tumor. — Size  3x3x3  cur. 

Macroscopic. — Pinkish-white  mass  of  resilient  tissue  with  villous  or 
papillary  surface,  enclosed  in  sac  of  denser  material,  (i)  premolar  and 
(2)  temporar\-  molar  embedded  in  wall. 

Microscopic. — Fibrocellular  stroma,  which  in  places  shows  small 
spaces  lined  with  columnar  epithelial  cells.  These  cells  are  much  elon- 
gated in  places,  and  the  nuclei  appear  to  be  situated  away  from  the 
connective-tissue  stroma,  as  in  the  ameloblasts.  Here  and  there, 
instead  of  a  cavity  lined  by  the  epithelial  cells,  the  space  appears  to 
be  tilled  with  stellate  reticulum. 


CHAPTER    VII. 

THE    NASAL   CAVITY   AND    ITS   ACCESSORY   CELLS 

AND   SINUSES. 

Descriptive  Anatomy. — The  nasal  cavities — the  internal  nose — con- 
sist of  two  chambers  situated  on  each  side  of  the  median  line  of  the 
face,  extending  downward  from  the  under  surface  of  the  anterior  portion 
of  the  brain-case  superiorly,  to  the  upper  surface  of  the  bones  forming 
the  hard  palate  inferiorly,  and  from  the  facial  border  of  the  external 
aperture  of  the  nose  anteriorly  to  the  free  border  of  the  external  ptery- 
goid plate  posteriorly.  They  are  lined  with  mucoperiosteum,  covered 
with  ciliated  epithelium;  and  the  membrane  is  continuous  with  the 
lining  of  the  several  sinuses,  cells,  and  passageways  of  this  region. 
On  the  upper,  lateral,  and  posterior  borders  of  the  nasal  cavity  there 
are  various  mucosa-lined  sinuses,  cells,  and  canals,  all  communicating 
with  the  cavity,  the  excess  of  fluids  secreted  by  them  passing  into  the 
nose.  The  nasolacrimal  ducts  conveying  the  excess  of  fluids  from  the 
anterior  surface  of  the  eyes,  the  auditory  tubes  communicating  with 
the  middle  ear,  and  the  maxillary  sinus,  the  frontal  sinus,  the  sphenoidal 
sinus,  the  ethmoidal  cells,  ethmosphenoidal  cells,  and  the  cells  belong- 
ing to  the  orbital  process  of  the  palate  bone,  have  their  outlets  in  the 
nasal  cavity.  The  cavities  are  separated  by  a  thin  partition  of  bone  and 
cartilage,  the  nasal  septum;  it  opens  on  the  anterior  surface  by  the 
anterior  nares.  The  two  principal  functions  of  the  nose  of  man  are 
concerned  with  respiration  and  with  the  special  sense  of  olfaction. 

The  middle  meatus  of  the  nasal  cavity  forms  the  principle  nasal 
passageway  for  the  air  into  the  respiratory  tract,  also  for  the  expired 
air  leaving  the  lungs.  The  upper  portion  of  that  part  of  the  cavity 
formed  by  the  ethmoid  bone  contains  the  beginning  of  the  olfactory 
organs.  As  it  is  necessary  to  their  function  that  these  parts  be  kept 
moist,    there    are    numerous    pockets    in    and    about    them,    the    lining 


DKSCRII'I  IVI-:  ASAIOMV  1<)7 

nu'iiihraiu'  ot  which  sccrL'tcs  iluids.  Tht-sc  fluids  j)ass  over  the  shcd- 
likc  projt'clions  ol  the  concha  Ikjhcs  into  the  nose,  supplying  the 
neceSvSar\'  moisture. 

Fiiis.  196  and  197  are  good  examples  of  the  nasal  cavities  showing 
bilateral  symnietr\'.  For  descriptive  convenience  it  may  be  divided 
into  roof,  Hoor,  and  outer  and  inner  walls,  the  last  named  being  formed 
by  the  medial  wall  or  nasal  septum. 

The  roof  of  the  nasal  cavity  is  long,  narrow,  and  irregular  in  form. 
It  is  divided  into  anterior,  middle,  and  posterior  sections. 

The  anterior  portion  is  formed  by  the  under  surface  of  the  nasal 
bones  and  the  nasal  spine  of  the  frontal  bone.  It  is  concave  from  side 
to  side,  and  extends  inward  and  ui)ward  to  the  ethmoid  bone,  at  an 
angle  of  about  forty- live  degrees. 

The  middle  portion  is  narrow,  nearly  horizontal  in  direction,  and 
is  comix)sed  of  the  under  surface  of  the  cribriform  plate  of  the  ethmoid 
bone,  through  the  openings  of  which  the  filaments  of  the  olfactory 
nerves  pass  between  the  nasal  cavities  and  the  brain.  Beside  the 
numerous  oi)enings  there  are  slit-like  foramina,  which  give  passage 
to  the  nasal  nerves  and  vessels.  The  cribriform  plate,  on  account 
of  its  thinness,  its  sieve-like  construction,  and  the  presence  of  the 
slit-like  openings,  affords  but  a  slight  {partition  between  the  nasal 
cavity  and  the  anterior  portion  of  the  brain-case. 

The  posterior  portion  of  the  roof  of  the  nose  is  the  longest  of  the 
three  parts,  and  extends  from  the  posterior  extremity  of  the  cribriform 
plate  obliquely  downward  and  backward  to  the  free  margin  of  the 
internal  i)terygoid  plate.  It  is  composed  of  the  bod>-  of  the  sphenoid 
bone  and  the  alcC  of  the  vomer. 

The  floor  of  the  nasal  cavity  extends  from  the  external  oi)ening 
anteriorly  to  the  pharyngeal  space  posteriorly .  It  is  smooth,  and 
concave  from  side  to  side.  The  bon\-  structure  is  composed,  anteriorly 
of  the  intermaxilla,  medialh-  of  the  palate  processes  of  the  maxillae, 
and  posteriorly  of  the  horizontal  plate  of  the  palate"  bone.  The  naris 
are  made  up  of  cartilage  lined  with  mucous  membrane,  and  form  the 
vestibule  of  the  nose.  In  the  normal  nose,  the  floor  joins  this  on  the 
same  plane  and  gradually  slopes  downward  and  backward  (see  Fig.  301). 


198        NASAL  CAVITY  AXD  ITS  ACCESSORY  CELLS  AXD  SIXUSES 

Occasionally  there  is  a  depression  immediately  back  of  the  union  of 
the  bone  and  cartilage.  The  floor  often  varies  in  its  relative  position 
to  the  other  structures.  It  is  seldom  on  the  same  level  as  the  floor  of 
the  maxillary  sinus;  it  may  be  on  either  a  higher  or  a  lower  plane. 
Examples  of  these  variations  are  seen  in  the  sections  shown  in  Figs.  261, 
262,  263  and  264. 

The  nasal  septum  (medial  wall)  forms  the  inner  walls  of  the  nasal 
cavities.  It  consists  of  six  bony  structures,  named  in  the  order  of  their 
importance — viz.,  the  vertical  plate  of  the  ethmoid,  the  vomer,  the 
crests  of  the  maxillae  and  palate  bones,  the  rostrum  of  the  sphenoid, 
and  the  nasal  spine  of  the  frontal  bone.  These  bones  do  not  form 
the  septum  completely,  but  leave  a  triangular  notch  in  the  anterior 
portion,  which  is  filled  up  with  cartilage. 

Septal  Spurs. — In  Figs.  195,  196  and  197  it  will  be  seen  that  the 
nasal  septum  is  nearly  vertical,  without  a  bend  or  a  nodular  process  or 
"spur"  upon  it.  It  is  commonly  thought  by  rhinologists  that  a  straight 
septum  is  unusual.  This  would  seem  to  be  an  error,  probably  due  to 
the  fact  that  the  great  majority  of  the  noses  which  they  examine  are 
abnormal.  It  is  quite  true  that  in  many  cases  the  septum  is  more  or 
less  deflected  to  one  side  or  the  other,  assuming  a  central  position  only 
as  it  passes  downward  and  nears  its  connection  with  the  floor  of  the 
cavit3^  On  the  convex  side  of  the  curve  in  these  cases  a  ridge  or  pro- 
cess is  often  found  which  is  called  a  "spur,"  and  which  may  extend 
quite  over  and  come  in  contact  with  the  external  wall  or  the  inferior 
concha  (see  Figs.  262,  263,  281,  292  and  293). 

Nasal  Meati. — The  lateral  wall  is  the  most  extended,  irregular, 
and  complicated  portion  of  the  nasal  fossa.  It  varies,  perhaps,  more 
in  its  general  formation  than  any  other  portion  of  the  body  of 
like  size,  and  is  correspondingly  difhcult  to  treat  surgically.  Several 
bones  enter  into  its  formation  on  each  side — viz.,  the  nasal,  maxillary, 
lacrimal,  ethmoid,  inferior  nasal  concha  and  palate  bones,  the  ptery- 
goid process,  and  the  body  of  the  sphenoid  bone.  By  the  projection 
of  the  inferior  nasal  concha  and  processes  of  the  ethmoid  bone,  the 
wall  is  divided  into  several  almost  horizontal  compartments  known 
as  meati.     The   anatomical   works  generally   name   three  meati — the 


XASAL   MEAT I 


199 


inferior,  tlic  niiddli'.  and  tlu-  suixrior.  Ziukcrkandl.  however,  says 
thai  al)()Ul  6,"„  per  ceiil.  of  ihe  skulls  examined  1)\-  liini  have  had  four 
meali.  The  writer  has  found  about  60  per  cent.,  with  four  meati  in 
the  skulls  of  which  he  has  made  sections  (see  Figs.  173  and  285). 
In  many  cases  there  are  live,  and  in  one  skull  six  were  found. 


Sella  turcica 


Auditory — 
orifice 


Right  frontal 
sinus 


Left  frontal 


Superior 

nasal  concha 
"^■iperior 
catus 

iiddle 

nasal  concha 

Middle 
meatus 


Inferior 

nasal  concha 
Inferior 

meatus 


Hard  palate 


—  Alveolar 
process 


Flc.  172. — Lateral  wall  of  a  left  nasal  cavity. 

Figs.  172  and  173  give  a  general  idea  of  the  arrangement  of  the 
outer  walls  of  the  nasal  cavity.  The  upi)er  portion,  or  all  of  that 
which  belongs  to  the  ethmoid  bone,  is  associated  with  olfaction.  The 
ends  of  the  nerves,  usualh'  called  the  terminals,  have  their  origin 
over  this  region;  they  also  are  distributed  o\er  the  upper  portion  of 


200 


XASAL  CAVITY  AXD  ITS  ACCESSORY  CELLS  AND  SINUSES 


the  ;:^L'ptuni  and  the  roof  of  the  nose.  The  fibers  converge  as  they 
pass  upward  to  form  the  filaments,  and  then  through  the  various  fora- 
mina in  the  cribriform  plate  of  the  ethmoid  bone  enter  the  olfactory 
bulb.  The  various  meati  have  communications  with  the  maxillary 
sinus  and  other  air  spaces  which  are  formed  in  the  bones  of  this  region. 


A  B 

Fig.  173. — Lateral  walls  of  the  nasal  cavities,  each  showing  four  nieatl. 


M^"^^ 


#Tl  ? 


A  B 

Fig.  174. — Lateral  walls  of  right  and    left  nasal    cavities,  with  large  sphenoidal  sinuses,  B,  ha\'ing 

four  meati. 

Fig.  174  gives  a  view  of  the  lateral  walls  of  the  nasal  cavity  of  the 
same  skull  as  Figs.  215  and  216.  The  sphenoidal  sinus  extends  later- 
ally until  it  forms  the  cavity  posterior  to  the  maxillary  sinus.  In  Figs. 
217  and  2i(S  it  will  be  observed  that  the  large  sphenoidal  sinus  extends 


y.lSOLAi  R/.\f.\I.  CAXALS 


201 


well  forward  toward  ihc  frontal  hone  and  backward  toward  tlic  basilar 
process  of  the  occipital  bone. 

Inferior  Meatus. — Tht'  inferior  meatus  is  situated  between  the 
inferior  nasal  concha  and  the  floor  of  the  nose.  It  is  much  lon!Li:er  than 
the  others. 


Frontal  sinus 


— -Middle  nasal  concha 


Ostium  maxillare 
-Middle  meatus 

Posterior  half  of  naso- 
lacrimal duct 

-Inferior  nasal  concha 


"Inferior  meatus 


Zygoma  Alveolar     Internal  wall  of 

process        maxillary  sinus 

Fig.  175. — Anterior  view  of  a  vertical  transverse  section  of  the  right  side  of  face. 

Nasolacrimal  Canals. — The  nasolacrimal  canals,  which  are  tor  the 
accommodation  of  the  nasolacrimal  ducts,  have  their  origin  in  the  inner 
anterior  lower  angle  of  the  orbits.  The  superior  orifices  commence 
between  the  nasal  processes  of  the  maxillae  and  the  lachrimal  bone. 
From  this  point  the  canals  extend  down  and  terminate  in  the  ui:)per 
portion  of  the  inferior  meatus  of  the  nose  (see  Figs.  175,  176.  177,  178 
and  179).  The  direction  of  their  descent  varies  considerabh  in  diflferent 
subjects,  and  even  in  the  same  subject.     They  usually  pass  backward, 


202 


X-15.1I  CAVITY  AXD  ITS  ACCESSORY  CELLS  AND  SINUSES 


and  when  the  maxillary  sinus  is  large  and  the  nasal  cavity  narrow, 
the  direction  may  be  inward;  where  the  maxillary  sinus  is  small  and 
the  nasal  cavit}'  wide,  the  direction  is  likely  to  be  outward.  In 
exceptional  cases  it  is  slightly  curved.  The  duct  may  have  a  valve 
composed  of  mucous  membrane  at  its  lower  extremity. 


Frontal  sinus 


Nasal  cavity 
Medial  wall  or  nasal  septum 

Inferior  nasal  concha 
Inferior  meatus 


;■,  -  rimal  duct 

-j^miipAnterior  half  of  nasolac- 
-BBM-Zygomatic  bone 


"■^ Anterior  wall  of 

maxillary  sinus 


Hard  palate     Alveolar  process 
P'iG.  176. — Posterior  view  of  a  vertical  section  cut  from  the  front  of  Fig.  175. 

Fig.  175  affords  an  anterior  view  of  a  section  cut  vertically  or 
longitudinally  through  the  nasolacrimal  duct,  showing  its  posterior 
portion  as  it  passes  from  the  orbit  downward  within  the  wall,  separating 
the  nasal  cavity  from  the  maxillary  sinus,  the  duct  terminating  in 
the  upper  portion  of  the  inferior  meatus.     On  the  upper  right  corner 


A^^ SOLA CKIMAL  CA NA LS 


203 


is  the  frontal  sinus.  To  the  Icfl  of  this  is  the  (jrbit.  in  tiie  centre  of 
the  wall  between  the  orbit  and  the  maxillary  sinus  will  be  seen  the 
infra-orbital  canal,  and  below  it  the  maxillary  sinus,  which  in  this 
case  is  very  large.  In  the  upper  portion  of  the  nasal  cavity  is  seen  the 
middle  nasal  concha,  below  which  a  cord  has  been  passed  from  the 
middle  meatus  through  the  ostium  maxillare  into  the  maxillary  sinus. 


Posterior  ethmoidal  cells 
Orbit 


Middle  meatus 

Af      -,1  '  ^si^BB^^H^^^^^^ic^  ^^P?'v^^Jl Middle  nasal  concha 

Maxillary  smus m^S^^^^^^^K^[^^'~  ^V ' 

Nasal  septum 

Inferior  nasal  concha 

Inferior  meatus 


Alveolar  process 
Fig.  177. — .Anterior  view  of  vertical  section  cut  posterior  to  that  shown  in  Fig.  176. 

Fig.  176  is  from  a  vertical  section,  cut  transversely  just  within 
the  infra-orbital  ridge.  In  the  upper  portion  is  the  anterior  wall  of 
the  frontal  sinus,  on  the  left  side  is  the  middle  wall,  and  to  the  right  of 
this  is  the  nasal  cavity.  The  anterior  half  of  the  nasolacrimal  duct, 
shown  in  the  previous  illustration,  will  be  seen  to  commence  at  the 
inner  angle  of  the  orbit  and  terminate  at  the  inferior  meatus. 


204 


.Y.15.1Z.  CAVirV  AXD  ITS  ACCESSORY  CELLS  AND  SINUSES 


Fig.  177  is  from  a  section  near  the  posterior  wall  of  the  maxillary 
sinus  and  the  orbits,  from  the  same  subject  as  Figs.  175  and  176.  It 
will  be  noticed  that  the  wall  of  the  maxillary  sinus  is  very  thin.  At 
the  upper  right  corner  are  seen  the  posterior  ethmoidal  cells,  below 
which  is  the  nasal  cavity. 

Fig.  178  is  from  a  section  showing  the  greater  portion  of  the  upper 
jaw.  The  upper  boundary  is  on  a  level  wdth  the  middle  of  the  orbits. 
Two  sounds  passed  down  into  the  nasolacrimal  ducts  indicate  that 


Fig.  178. — Section  showing  the  greater  portion  of  the  upper  jaw.  S,  S,  sounds  passed  down  the 
nasolacrimal  ducts,  showing  that  they  do  not  pass  at  the  same  angle.  The  illustration  also  shows 
an  impacted  canine  tooth.     (For  description  see  page  177.) 


the  ducts  pass  outwardly  as  they  descend  into  the  upper  part  of  the 
inferior  meatus.  It  will  be  observed  that  the  right  duct  has  a  greater 
outward  deflection  than  the  left. 

The  horizontal  line  above  the  roots  of  the  teeth  and  below  the 
zygoma  makes  a  division  of  the  section  just  above  the  floor  of  the 
nasal  cavity.  The  under  surface  of  the  upper  portion  is  shown  in 
Fig.  179,  which  affords  a  view  of  the  surface  of  the  inferior  concha 
from  below,  with  the  lower  orifices  of  the  nasolacrimal  duct.  It  also 
shows  the  lower  edges  of    the  middle  and   superior  concha,  and   the 


.V.I.VO/..ICA7.1/.I/.   C.I.V.IA.V 


2(i: 


roofs  of  the  antra.     Atlaclud  l(j  llic  vooi  of  llu-  ri;j,lu   maxillary  sinus 
arc  two  abnormal  hoiu   j^rowths  gencTall>'  known  as  osl('0])h\'tc'S, 

The  middle  meatus  is  situated  Ix-twcen  the  lower  jjorlion  of  the 
concha  of  the  ethmoid  hone  and  the  inferior  concha,  and  forms 
two-thirds  of  the  posterior  i)()rti(jn  of  the  outer  wall  of  the  nasal 
ca\it\-.     This  is  the  most  important  meatus,  as  it  is  the  princii)le  nasal 


Osteophytes 


Superior      Middle 
concha      meatus 

Fig.  179. — Horizontal  section,  showing  the  under  surfaces  of  the  inferior  concha  and  the  outlet  of 

the  nasolacrimal  duct. 

passap:cway  of  respiration,  and  is  subject  to  more  variations  in  its 
anatom>',  ph>siology,  and  patholog\-  than  are  all  the  others.  It  has 
anatomical  communications  with  the  frontal  and  maxillary-  sinuses, 
and  with  the  anterior  and  middle  ethmoidal  cells.  In  order  to  study 
this  meatus  and  its  relations,  it  is  necessary-  to  make  a  number  of 
sections  of  the  parts  with  all  the  tissues  in  place.  By  removing  the 
middle  concha,  the  structure  of  the  parts  is  brought  into  view. 


206 


XASAL  CAVITY  AXD  ITS  ACCESSORY  CELLS  AND  SINUSES 


Fig.  1 80  shows  the  outer  wall  of  the  nasal  cavity  with  the  internal 
wall  of  the  middle  concha  of  the  ethmoid  bone  cut  loose  and  turned 
up,  affording  a  good  idea  of  the  normal  anatomy  of  this  region.  The 
frontal  sinuses  are  exposed.     In  the  illustration  the  right  frontal  sinus 


Section  turned  tip 


Posterior  ethmoidal  cells 


Sella  turcica 


Auditory 
orifice 


Right  frontal 
sinus 


Left  frontal 
sinus 


Infundibulum 

Anterior  eth- 
moidal cells 

Hiatus 
semilunaris 

Unciform 
process 

-  Middle 
meatus 

Inferior 

concha 
Probe  passing 

into  lacrimal 

duct 
Inferior 

meatus 


Hard  palate 


Alveolar 
process 


Fig.  180. — An  anteroposterior  section  within  the  nasal  cavity,  with  the  middle  concha  and  portion 

of  the  cell  walls  turned  up. 

extends  over  the  left  side  of  the  medial  line.  The  open  space  imme- 
diately below  this  is  the  left  frontal  sinus.  The  partition  between  these 
sinuses  in  some  places  is  thin.  The  lower  portion  of  the  left  frontal 
sinus  is  funnel-shaped.      This  opens  into   a  passage  leading  into  the 


///.  I  ri  'S  SEMILLSA  RIS  207 

middle  nicatus,  tlu'  luiincl-sliaijcd  i)()rti()n  and  the  passage  being 
commonly  called  the  infiindii)iilum.  This  illustration  also  gives  a 
good  idea  of  the  nasal  surface  of  the  partition  between  the  maxillary 
sinus  and  the  great  extent  of  the  mucous-lined  sinuses  and  cells  that 
are  so  directh'  related  with  it.  When  these  pneumatic  spaces  become 
diseased,  it  is  almost  impossible  to  keep  the  sinuses  in  hygienic  condi- 
tion, and  when  the  infection  reaches  them,  they  are  much  more  diffi- 
cult to  treat  and  drain  than  when  the  disturbance  comes  from  the 
teeth  or  alveolar  process. 

Hiatus  Semilunaris. — The  infundibulum  is  often  included  in  the 
part  which  has  been  named  by  Zuckerkandl  the  hiatus  semilunaris, 
and  which  extends  from  the  frontal  sinus  to  and  through  the  middle 
meatus  in  the  form  of  a  semicircular  groove  or  cleft  along  the  outer 
wall  of  the  meatus.  It  extends  downward  and  backward  in  a  curved 
direction,  being  horizontal  in  its  posterior  portion,  and  terminates 
a  little  behind  the  centre  of  the  nasal  cavity.  At  its  commencement 
it  is  narrow,  but  it  widens  as  it  passes  downward  and  backward,  its 
widest  part  being  at  the  bottom  and  near  the  o])ening  between  the 
maxillary  sinus  and  the  nasal  cavity  (ostium  maxillarc).  Besides 
the  opening  of  the  frontal  sinus  into  the  hiatus  semilunaris,  there  are 
openings  from  the  anterior  and  middle  ethmoidal  cells,  and  from  the 
maxillary  sinus.  Its  inner  boundary  is  falciform  in  shape,  and  is 
composed  of  the  uncinate  process  of  the  ethmoid  bone  with  mem- 
branous tissue,  forming  a  shield  or  guard  to  the  opening  of  the  maxil- 
lary sinus,  to  prevent  foreign  substance  from  passing  into  it. 

A  "sound"  cannot  be  passed  from  the  nasal  cavity  through  the 
ostium  maxillare  into  the  maxillary  sinus  in  a  normal  living  person. 

The  superior  meatus  is  shallow,  and  is  shorter  than  the  inferior 
or  middle  meatus.  It  is  situated  between  the  superior  and  inferior 
concha  masses  of  the  ethmoid  bone,  and  in  the  articulated  skull  between 
the  superior  and  middle  concha.  The  cell  situated  in  the  orbital  pro- 
cess of  the  palate  bone,  the  posterior  ethmoidal  cells,  and  the  sphenoi- 
dal sinus  all  have  their  openings  into  this  meatus  when  there  are  but 
three  meati,  but  when  there  are  four,  the  posterior  ethmoidal  cells 
and  the  sphenoidal  sinus  have  their  openings  into  the  fourth  or  superior 


208        XASAL  CAVITY  AXD  ITS  ACCESSORY  CELLS  AND  SINUSES 

meatus.  If  there  are  five  mcati  the  sphenoidal  sinus  usually  opens 
into  the  fifth.  In  other  words,  this  sinus  has  a  tendency  to  open  into 
the  highest  meatus. 

The  fourth  or  superior  meatus  of  Zuckerkandl  is  formed  by  an 
infolding"  of  a  portion  of  the  concha  similar  to  that  of  the  third  or 
superior  meatus,  though  smaller  in  extent.  When  the  fourth  meatus 
exists,  the  fluids  of  the  posterior  ethmoidal  cells  and  those  from  the 
sphenoidal  sinus  pass  through  it  to  reach  the  nasal  cavity. 

The  occasional  fifth  meatus  is  formed  similarly  to  the  third  and 
fourth  meati  b}'  an  infolding  of  the  upper  portion  of  the  ethmoid 
mass.  In  such  cases  the  fluids  from  the  sphenoidal  sinus  pass  through 
it  instead  of  into  the  fourth. 


PATHOLOGICAL    CONDITION    OF    THE    NASAL    CAVITY. 

Pathological  Conditions  of  the  Bulla  Ethmoidalis. — Through  patho- 
logical increase  in  the  size  of  the  hulla  ethmoidalis,  disturbances  may  be 
caused  in  the  anterior  and  superior  portion  of  the  nasal  cavity,  in  the 
frontal  sinus,  and  maxillary  sinus,  for  by  its  enlargement  toward  the 
median  line  it  presses  toward  and  against  the  septum  of  the  nose, 
closing  the  space  of  the  nasal  cavity.  If  this  enlargement  is  downward 
it  presses  more  upon  the  unciform  process  and  into  the  hiatus  semi- 
lunaris, closing  it  and  preventing  the  passage  of  fluids  from  the  frontal 
sinuses  and  the  anterior  ethmoidal  cells  into  the  posterior  portion  of 
the  middle  meatus,  and  forcing  them  to  enter  the  maxillary  sinus. 
Through  general  inflammation  of  the  parts  there  may  result  an  excess 
of  fluids  w^hich  cannot  find  exit.  This  would  interfere  with  the  vitality 
of  the  teeth  through  pressure  upon  the  nerves  and  vessels  passing 
through  the  maxillary  sinus.  It  would  cause  a  feeling  of  fulness  of 
all  the  anterior  cells,  as  well  as  the  frontal  sinus,  and  might  even  set 
up  disturbance  in  the  anterior  portion  of  the  brain-case. 

A  view  of  the  nasal  septum  as  seen  from  the  left  nasal  cavity  is 
shown  in  Fig.  i8i.  An  opening  in  the  septum  exposes  to  view  the 
bulla  ethmoidalis  and  the  ethmoidal  cells.  This  opening  resulted  from 
resorption  caused  by  pressure  due  to  the  deflection  of  the  septum  and 


PATHOLOGICAL  CONDITION  OF  NASAL  CAVITY  209 

the  cnlargcmcMit  of  llic  bulla  cUnvnward  near  the  unciform  process. 
We  have  here  illustrated  an  example  showing  how  enlargement  of  this 
structure  ma\  be  an  important  factor  in  causing  various  diseases  of 
this  region,  including  those  of  the  maxillary  and  frontal  sinuses. 

Fig.  182  gives  a  view  of  the  same  subject  as  Fig.  181,  from  the  same 
direction,  but  with  the  septum  removed,  exposing  the  inner  surface 
of  the  outer  wall  of  the  right  nasal  cavity.  Of  the  two  openings  into 
the  maxillary  sinus  as  seen  in  this  i)iclure,  the  anterior  (jne  is  normal, 
the  posterior  is  pathological.     This  abnormal  opening  and  the  loss  of 


Fig.  181  P'ig.  182 

Fig.  181. — The  left  side  of  the  medial    wall,  showing  a    pathological    opening    opposite    the 

bulla  ethmoidalis. 

Fig.  182. — Same  specimen  with  the  septum    removed,    showing   abnormal    opening    into    the 

maxillary  sinus. 

the  greater  portion  of  the  middle  concha  were  caused  by  resorption 
due  to  the  pressure  of  the  bulla  ethmoidalis  before  referred  to. 

The  effect  of  blocking  up  the  hiatus  semilunaris,  causing  the 
secondary  or  associated  openings  between  the  sinus  and  the  nasal 
cavities,  is  also  shown  in  Fig.  185. 

Figs.  183  and  184  show  two  pictures  from  the  left  side  of  the  same 
skull  shown  in  Figs.  181  and  182.  In  Fig.  184  the  middle  concha  is  in 
position.  The  abnormal  opening  into  the  nasal  cavit\-,  seen  near  the 
centre  of  the  picture,  was  probably  the  result  of  the  closure  of  the 

14 


210 


XASAL  CAVITY  AXD  ITS  ACCESSORY  CELLS  AND  SINUSES 


hiatus  semilunaris,  shown  in  Fig.  183.  In  this  the  middle  and  a  portion 
of  the  superior  concha  are  cut  loose  and  turned  upward,  to  expose  the 
bulla  ethmoidalis  extending"  downward  and  closing  the  hiatus.    This 


r  "^        ^JMWWW*"^^         : 


Fig.  183  Fig.  184 

Figs.  183  and  184. — Two  pictures  of  the  left  nasal  cavity  from  the  same  subject  as  Figs.  181 
and  182,  showing  a  pathological  opening  into  the  maxillary  sinus  in  Fig.  184.  Fig.  183,  the  same 
specimen  as  Fig.  184  with  a  portion  of  the  middle  and  superior  conchas  cut  loose  and  turned  up. 


Fig.  185  Fig.  186 

Pigs.  185  and  186. — Anteroposterior  sections.  Fig.  185  through  the  nasal  cavity,  Fig.  186  through 
the  maxillary  sinus.  The  former  shows  a  divided  bulla  ethmoidalis,  the  latter  shows  two  ostia 
maxillaria,  one  being  pathological. 

closure  would  compel  the  fluids  from  the  frontal  sinus  and  the  anterior 
and  middle  ethmoidal  cells  to  pass  into  the  maxillary  sinus. 

Figs.  185  and  i86  show  two  anteroposterior  sections  from  another 
skull  in  which  the  Ijulla  ethmoidalis  has  become  enlarged.     Fig.   i86 


PM  llOHKilCAL  L().\/)/J/(}.\    Ol-    .\.\SAL  CAVITY 


211 


has  the  outer  wall  of  (lie  nuixiUarx'  sinus  removed,  showini;  the  inner 
wall  with  two  outlets  al  its  upi)er  niaruin.  'Hie  anterior  opening  is 
the  normal  ostium  maxillare.  The  j)osterior  one  is  pathological  and 
similar  to  those  shown  in  I'igs.  icSi,  1S2,  183  and  1S4,  hut  in  this  case 
the  Ojicning  is  nearer  the  roof  of  the  sinus.  Fig.  i  .S5  is  cut  frt^ii  the 
inner  side  of  Fig  186. 

Figs.  187  and  188  illustrate  the  same  sections  as  Figs.  185  and 
186  with  Fig.  188  tiu'ued  roimd  to  the  left  side  of  the  other.  The 
illustration  affords  a  \iew  of  the  nasal  ca\'it>'  di\ided  through  the 
hiatus  semilimaris,  the  bulla  ethnioidalis,  and  the  posterior  ethnKjidal 
cells.    Fig.  188  shows  the  lateral  wall  of  the  nasal  cavity  with  a  greater 


Fig.  187  Fig.  188 

Figs.    187    and    188. — Anteroposterior   sections,  cut  apart   ttirough   tlie  frontal  sinus,  the  hiatus 

semilunaris,  the  bulla  ethnioidalis,  and  the   posterior  ethmoidal  cells. 

portion  of  the  concha?  removed.  Fig.  187  shows  the  septum  of  the 
nose.  The  two  together  give  a  very  clear  idea  of  the  character  of 
the  hiatus  semilunaris  and  the  bulla  ethmoidalis.  In  this  case  the 
bulla  is  very  large  and  extends  downward  and  forward,  closing  the 
hiatus.  The  illustration  is  taken  from  a  dried  specimen,  showing  an 
incomplete  closure,  w'hich  in  the  recent  state  must  have  been  complete. 
This  would  have  caused  the  fluids  from  the  frontal  sinus  and  the  eth- 
moidal cells  anterior  to  the  closure  to  be  directed  into  the  maxillary  sinus, 
as  the  ostium  maxillare  is  also  anterior  to  the  bulla  ethmoidalis.  The 
maxillary  sinus  would  become  engorged  with  these  fluids,  which  would 
naturally  make  their  way  through  the  walls  in  the  direction  of  the 


212        NASAL  CAVITY  AXD  ITS  ACCESSORY  CELLS  AND  SINUSES 

least  resistance — in  this  case  at  the  abnormal  opening  shown  in 
Fig.  1 86.  These  sections  also  illustrate  a  condition  sometimes  met 
with,  when  the  hard  palate  is  unusually  flat.  In  such  cases  the 
floor  of  the  nose,  instead  of  being  horizontal,  is  depressed  about  the 
middle,  giving  a  concavity  which  affords  a  lodgment  for  inspissated 
mucus.  The  same  condition  may  also  occur  in  the  floor  of  the  nose, 
when  the  inferior  meatus  is  occluded,  as  shown  in  Fig.  262,  and  is 
also  found  in  other  spaces  in  and  about  the  nasal  cavity.     Collections 


B 
Fig.  189. — A  shows  the  roof  of  the  nasal  cavity  and  the  maxillary  sinus,  B  shows  the  floor  of  the 
anterior  fossa  of  the  brain-case  and  part  of  the  frontal  sinuses,  to  one  of  which  there  is  no  foramen 
of  exit. 

of  this  character  often  produce  irritation  of  the  mucous  membrane 
interfering  with  the  nourishment  of  the  bone  beneath,  and  at  times 
causing  a  necrotic  condition. 

Occlusion  of  the  Outlets  of  the  Frontal  Sinus. — In  Fig.  189,  B  shows 
a  horizontal  section  through  the  anterior  fossae  of  the  brain-case  and 
through  the  frontal  sinuses,  from  one  of  which  there  has  been  no  fora- 
men of  exit,  an  example  of  unilateral  occlusion.  A  view  of  the  roofs 
of  the  maxillary  sinuses  and  of  the  nasal  cavity  is  given  in  A. 

The  section    shown    in    Fig.   190    is    made  from  the  same  subject 


PATHOLOGICAL  CONDITION  OF  NASAL  CAVITY  213 

as  Fi^.  189,0110  inch  l)c-l()\\  B.  Il  (.•xhibils  ihe  (!(n\  iiw  aid  (.'xca\  a- 
tion  which  has  occurred  in  the  occUulcd  sinus.  In  the  lower  surface, 
A,  is  shown  the  excavation  exlenchn;^  in  the  (Hrection  of  the  nasal  s])ine. 
There  are  marked  irretiularities  in  the  ethmoidal  cells  of  the  two  sides. 
Fig.  191  also  illustrates  unilateral  occlusion.  This  section  displays 
the  floor  of  the  brain-case,  showing  a  perforation  at  the  point  indicated 
1)\-  the  thread  passing  through  it.  It  is  reasonable  to  suppose  that 
the  retained  fluids  have  burnnved  through  the  cribriform  plate,  causing 


^. 


li 

Fig.  190. — Horizontal  sections  in  same  subject  as  Fig.  189,  sliowing  surfaces  cut  through  the  middle 

of  the  orbits  and  the  upper  part  of  the  nasal  cavity. 

the  perforation.  The  crista  galli  in  the  specimen,  although  not  clearly 
shown  in  the  picture,  is  bent  downward  until  almost  flat  by  what 
has  evidently  been  a  cyst  or  tumor  within  the  brain-case  in  this  region. 
Unfortunately,  the  writer  w^as  unable  to  obtain  antemortem  or  clear 
postmortem  notes  of  these  two  cases.  It  might  be  supposed,  however, 
that  the  patients  presented  cerebral  symptoms.  In  conhrmation  of 
this  idea,  there  was  evidence  in  the  condition  of  the  skulls  that  there 
had  been  a  postmortem  examination  of  them. 


214        XASAL  CAVITY  AXD  ITS  ACCESSORY  CELLS  AND  SINUSES 

Fig.  192  is  from  the  same  specimen  as  Fig.  191.  It  shows  the  effects 
of  the  encroachment  of  the  inflammatory  and  necrotic  condition  upon 
the  internal  wall  of  the  orbit. 


Fig.  191. — Horizontal  section,  showing  the  floor  of  the  anterior  fossa  of  the  brain-case  and  part 
of  the  frontal  sinuses.  The  right  sinus  had  no  outlet  into  the  hiatus  semilunaris,  but  had  an  outlet 
into  the  anterior  fossa  of  the  brain-case. 


Fig.   192. — From  same  suljject  as  I'ig.   191.     View  showing  diseased  condition  of  the  inner 

wall  of  the  orbit. 

Fig.  193,  from  the  same  specimen,  shows  a  horizontal  section  made 
through  the  ethmoidal  cells,  the  nasal  fossae,  etc.,  along  the  line  indi- 
cated in  Fig.    192.     The  two  faces  of  the  si}ecimen  show  clearly  the 


iwriioixKiicAL  cosniriox  of  .v.i.v.ia  cavity 


215 


hrokcii-dow  11  coiidilion  ijiodiicid  in  llu-  track  ol  ihe  disease.  The 
ahiiornial  arraniic'iiu'iu  of  the  c-ells  lu'conies  especially  apparent  when 
C()nii)are(l  witii  tlie  iNpical  arran.ncnient  shown  in  Fii;s.  257  and  25H. 


Fig.  193. — From  the  same  subject  as  Figs.  191  and  192.     Horizontal  division  through  the  orbits 
and  ethmoidal  cells,  showing  the  diseased  condition  of  these  cells. 


Obstruction  of  Fluids. — There  is  a  fundamental  law  of  surgery 
that,  wherever  an  obstruction  of  any  of  the  passages  within  the  body 
exists,  it  should  be  removed,  and  if  possible  the  course  of  fluids  be 
reestablished  in  their  normal  channels  or  conduits.  If  the  hiatus  semi- 
lunaris, which  is  the  outlet  of  the  fluids  of  the  frontal  sinus,  becomes 
closed  in  aiu'  portion,  or  at  the  inlets,  by  bony  or  other  growths,  it  is 


21()       XASAL  CAVITY  AXD  ITS  ACCESSORY  CELLS  AND  SINUSES 

good  and  proper  surgery  to  remove  this  obstruction.  If  the  fluids 
from  the  various  sinuses  and  cells  are  allowed  to  accumulate  in  the 
maxillary  sinus  without  an  opportunity  to  escape  back  into  the  nasal 
cavity,  through  a  pathological  or  surgical  opening,  the  teeth  and 
their  alveolar  processes  are  liable  to  become  involved. 

The  mouth  should  by  all  means  be  kept  free  from  foul  discharge, 
and  such  proper  surgical  procedure  instituted  as  will  restore  the  natural 
outlets  without  infecting  the  oral  cavity,  as  by  the  action  of  mastica- 
tion, septic  fluids  become  mixed  with  the  food  and  are  thus  distributed 
through  the  alimentary  canal  to  infect  the  entire  system. 


(MIA  rTi:  R   \'  I  I  !. 

THK   MAXILL.\R\    SINUS. 

The  maxillarx  sinus  {inilnini  of  Ilighmore)  is  situated  in  the  body 
of  the  maxilla?,  and  is  the  largest  air  space  associated  with  the  nasal 
cavity.  It  varies  in  shape,  size,  and  in  the  thickness  of  its  walls,  accord- 
ing to  age,  race,  and  the  j^resence  or  absence  of  teeth  and  tooth-germs 


Fig.  194. — A  horizontal  section  of  face  cut  just  above  the  floor  of  the  nasal  cavity. 

within  the  jaw.  It  is  lined  with  mucoperiosteum  surmounted  by  ciliated 
epithelium.  The  typical  sinus  is  pyramidal  in  shape,  the  apex  bemg 
toward  the  zyomatic  bone — into  which  it  may  extend  (see  Fig.  271) — 
and  the  base  toward  the  nasal  cavitw     Its  size  and  form  \av\  in  different 


21S 


THE  MAXILLARY  SINUS 


subjects,  and  e\en  in  the  two  sides  of  the  same  subject  (see  Figs.  263, 
264,  265  and  266).  In  rare  cases,  it  is  lacking  on  one  or  both  sides 
(see  Fig.  194). 

Fig.  194  shows  two  horizontal  sections.  The  lower  one  giving  a 
good  \"iew  of  a  very  wide  floor  of  the  nasal  cavity.  The  upper  one 
showing  the  walls  of  the  nasal  cavity,  the  concha  bones  and  the  septum. 


Anterior  fossa  of 
brain-case 
Crista  galli 

—  Orbit 

Medial  wall  of 
nasal  cavity 
Ostium  maxillare 
Maxillary  sinus 
Zygoma 
Maxilla 


Dental  germs 


Mandible 


Fig.  195. — Skull  of  a  fully  developed  embryo  cut  vertically  through  the  first  deciduous  premolars. 

On  the  right  side  there  is  no  maxillary  sinus  and  on  the  left  the  sinus 
is  very  small,  thus  accounting  for  a  wide  nasal  cavity. 

Fig.  195  is  a  view  of  the  skull  of  a  fully  developed  embryo.^  It  is 
a  transverse  section  cut  vertically  just  within  the  floor  of  the  orbit. 
In  the  upper  portion  are  seen  two  openings  into  the  brain-case  with 
the  crista  galli  and  falx  cerebri  between  them,  below  which  is  the  nasal 
cavity  with  its  septum.    Projecting  from  the  outer  wall  of  the  cavity 


From  the  collection  of  i'rofessor  Thomas  C.  Stellwagen. 


DIAELOPMEST  21'.) 

arc  llu'  niiddk'  and  inl\  rior  concha.  In  llic  middle  meatus  may  be  seen 
the  unciform  process  i)assin,u  ui)\vard  and  a  little  inward  Irom  the 
base  of  the  inferior  concha.  Al  tlu-  outer  side  of  this  is  the  passageway 
known  as  the  hiatus  semilunaris,  into  which  the  ostium  maxillare 
passes  from  the  maxillary  sinus,  which  is  very  small  at  this  period  of 
embryonic  life. 

Development. — The  development  of  the  sinus  begins  about  the 
fourth  month  of  intra-uterine  life  by  an  invagination  of  the  lining 
membrane  of  the  nose  from  the  hiatus  semilunaris  into  the  body  of 
the  maxilla.  From  the  time  of  the  invagination  until  the  eruption  of  the 
permanent  teeth,  the  greater  jwrtion  of  the  maxilla  is  occupied  by 
the  dental  organs  (see  Fig.  137).  As  the  invagination  progresses,  the 
cancellated  portion  of  the  bone  undergoes  resorption.  This  resorption 
of  the  internal  portion  of  the  maxilla  is  continued  in  a  variable  degree 
throughout  life,  until  in  old  age  the  walls  usually  become  exceedingly 
thin,  as  shown  in  Fig.  205.  In  some  cases  the  decalcification  and 
resorption  are  carried  to  such  an  extent  that  the  entire  bone  is  thinned, 
and  an  ordinary  lancet  blade  can  be  easily  passed  through  the  wall 
into  the  sinus,  or  the  entire  substance  of  the  bone  may  be  resorbed  in 
places,  leaving  nothing  but  the  mucoperiosteum  at  these  points.  i\s 
this  process  goes  on,  the  roots  of  the  premolars  and  molars  within  the 
walls  are  approached,  until  in  many  places  the  points  of  the  roots  are 
covered  only  by  a  thin  lamina  of  bone  (see  Figs.  202  and  203).  Fven 
this,  in  rare  cases,  may  be  lost,  leaving  only  the  mucoperiosteum  as 
a  root-covering. 

At  first  the  sinus  has  a  spheroidal  shape,  but  it  eventually  ap- 
proaches the  pyramidal  form.  Its  walls  are  five  in  number,  the  inferior 
or  floor,  the  anterior  or  facial,  the  posterior  or  zygomatic,  the  superior 
or  roof,  and  the  proximal  or  nasal. 

Fig.  196  is  an  excellent  illustration  of  a  transverse  bilateral  section 
cut  vertically  through  the  anterior  portion  of  the  orbit,  the  maxillary 
sinus,  and  the  first  molar  of  each  jaw,  dividing  the  eye  just  in  front 
of  the  crystalline  lens.  In  the  upper  portions  of  the  nasal  cavities  are 
seen  the  middle  ethmoid  cells.  At  about  the  centre  of  the  floor  of  the 
orbit  and  the  roof  of  the  sinus,  which  is  ver\-  thin  in  this  case,  will 


220 


THE  MAXILLARY  SINUS 


be  found  the  infraorbital  canal  as  commonly  described,  and  below, 
the  nearh-  pyramidal  cavity  of  the  maxillary  sinus,  with  a  partial 
septum  crossing  transversely  from  the  inner  to  the  outer  wall. 


Crvstalline  lens 


Unciform  process 
Middle  concha 
Middle  meatus 
Maxillary  sinus 
Inferior  meatus 

Inferior  nasal 
concha 


Vestibule  of  the 

mouth 
First  molar 


Posterior  root  of 
first  molar 


Inferior  alveolar 
nerve 


Fig.  196. — Anterior  view  of  a  vertical  transverse  section  of  the  head,  showing  the  relations  of  the 
jaws,  and  indicating;  the  positions  of  the  conchae,  antra,  etc. 

In  the  lower  angle  of  the  left  sinus  can  be  seen  the  anterior  buccal 
root  of  the  second  molar,  while  on  the  inner  wall  is  a  portion  of  the 
palatal  root  of  the  first  molar.  The  palatal  root  of  the  right  first 
molar  is  easily  seen  passing  well  u\)  in  the  inner  wall  of  the  sinus. 


IJIAKLOPMJ.XT 


221 


The  rcntriil  i)()rli()ns  afford  cxcclk-nl  \icws  of  transverse  sec- 
tions of  the  nasal  ea\il\'.  The  septum  in  the  centre  is  unusualh- 
straight.  Abow  llic  septum  is  the  crista  galh,  to  which  the  falx  ctrcl)ri 
is  attached  antiriorly.  On  each  side  of  the  sej)tum,  at  the  upper 
attachment,  is  the  roof  of  the  nasal  cavity,  below  at  a  little  distance 
are  the  middle  conchie,  and,  on  the  outer  wall,  are  the  inferior  concha. 
The  superior  conchae  cannot  be  seen  in  a  section  cut  in  this  region,  as 
the\'  are  situated  farther  back  in  tlic  skull. 


First  molar  First  molar 

Fig.  197. — Posterior  view  of  vertical  transverse  section  of  the  head  from  the  same  skull  as  Fig.  196, 
showing  the  ostium  maxillare,  which  is  indicated  on  each  side  by  a  cord  passed  through  it. 


Fig.  197  represents  the  anterior  portion  of  the  same  skull  shown 
in  Fig.  196.  At  the  anterior  superior  angle  of  the  maxillary  sinus  is  a 
cord  marking  the  passage  (ostium  maxillare)  from  the  sinus  into  the 
hiatus  semilunaris.  In  the  floor  of  the  maxillary-  sinus  will  be  seen  the 
septum  referred  to  in  the  description  of  Fig.  196.  On  the  left  side 
will  be  observed  the  palatal  and  anterior  buccal  roots  of  the  first  molar 
in  the  outer  and  inner  walls  of  the  sinus.  The  positions  of  these  roots, 
as  shown   here  and   in  Fig.   196,  are   very  interesting  from    a   dental 


999 


THE  MAXILLARY  SINUS 


standpoint.  The  extraction  of  teeth  having  roots  in  such  positions, 
if  not  carefully  done,  might  carry  away  parts  of  the  floor  of  the  sinus 
(see  Figs.  231,  232  and  233),  or  in  case  of  breakage  in  extracting,  the 
roots  could  easily  be  forced  into  the  sinus  by  injudicious  use  of  the 
forceps.  Also,  by  using  too  much  force  in  placing  artificial  crowns, 
the  floor  might  be  fractured. 


F"iG.  198. — X-ray  of  a  dried  skull. 

In  the  majority  of  the  skulls  belonging  to  the  white  races,  roots 
of  the  molar  teeth  pass  up  into  the  walls  of  the  maxillary  sinus,  being 
covered  at  the  point  where  they  approach  the  surface  by  a  thin  conical 
portion  of  bone. 

Fig.  198  is  from  a  radiograph  of  the  anterior  portion  of  the  face, 
showing   two   large  frontal  sinuses.     Two  wires  may  be  seen  passing 


DEVELOVMEM'  223 

downward  tlirous^li  llir  osliuni  frontalis  into  the  hiatus  scniikmaris, 
and  then  into  thi.'  nia\illar>'  sinus,  l)y  the  ostium  maxillarc.  The 
infra-orbital  sinus  and  the  inferior  and  middle  conchseare  seen,  also  two 
large  cells  between  tlu-  i)Iates  of  the  latter. 

When  the  maxillary  sinus  is  large  early  in  life,  and  extends  down- 
ward into  the  region  of  the  roots  of  the  teeth,  it  prevents  their  normal 
development  in  shape  and  positicjn,  the  roots  grow  curved  and  in  the 
case  of  molars,  are  compressed  (see  Figs.  202  and  203).  After  early 
middle  life,  as  the  dentine  forms,  the  pulp  canals  become  more  or  less 
narrowed  until  the  nerves  are  impinged  upon,  causing  pain  (neuralgia). 

Fig.  199  is  an  .v-ray  picture  of  a  large  maxillary  sinus,  showing  that 
it  has  ai)parentK-  extended  downward  between  the  roots  of  the  second 
premolar  and  the  first  molar;  from  the  shape  and  position  of  the  roots, 
especially  of  the  first  and  second  molar  teeth,  it  is  evident  that  the 
sinus  was  over  size  before  these  teeth  were  developed.  In  this  par- 
ticular case  the  patient  suffered  from  severe  neuralgia  of  the  upper 
jaw.  The  .v-ray  showed  the  condition,  and  after  removal  of  the  first 
molar  the  pain  subsided. 

Fig.  200  shows  a  section  similar  in  character  to  Figs.  196  and  197, 
but  from  a  negro  skull.  The  greater  thickness  of  the  floor  of  the 
maxillary  sinus,  and  the  position  of  the  roots  of  the  teeth  are  note- 
worth>-.  In  the  negro  race  the  walls  and  the  floor  are  much  thicker 
than  in  the  white;  therefore,  as  a  rule,  the  roots  of  the  teeth  do  not 
pass  up  into  the  wall,  or  even  near  the  floor  of  the  sinus. 

Fig.  201  is  an  illustration  of  a  tooth  which  has  been  perforated 
by  a  drill  while  in  the  mouth,  the  operator  supposing  his  drill  was 
passing  up  the  palatal  root,  instead  of  which  it  passed  through  the 
pulp  chamber,  the  base  of  the  crown,  the  alveolar  process,  and  into 
the  maxillary  sinus.  It  will  be  observed  that  in  extracting  it,  a  portion 
of  the  floor  of  the  sinus  has  been  brought  away  with  the  tooth.  At 
the  time  of  extraction  the  patient  was  suffering  from  empyema  of  the 
maxillary  sinus. 

The  Floor. — The  floor  of  the  maxillary  sinus  is  somewhat  triangular 
in  its  general  outline,  and  is  usually  uneven,  owing  to  the  presence 
of  partial  septa  and  conical  elevations  over  the  roots  of  the  various 


224 


THE  MAXILLARY  SINUS 


teeth.  These  elevations  are  found  over  the  roots  of  the  molars,  some- 
times over  those  of  the  premolars,  and  less  frequently  over  those  of 
the  canine  teeth.  As  age  advances  and  the  teeth  underlying  the  sinus 
are  lost,  the  floor  becomes  comparatively  smooth.  Septa  may  extend 
to  various  heights  transversely  from  side  to  side  or  anteroposteriorly 
(see  Figs.  205  and  206),  forming  deep  pockets  between  them.     The 


Fig.  199. — Showing  where  a  maxillary  sinus  has  been  large  at  the  time  of  the  developing  of  the  roots 
of  second  premolar  and  first  and  second  molar  teeth.     (X-ray  by  Dr.  Pfahler.) 

floor  of  the  sinus  may  descend  between  the  roots  of  the  molar  teeth, 
as  shown  in  Figs.  196  and  197.  It  may  also  descend  between  the 
teeth  (see  Fig.  199),  a  condition  much  more  common  among  the  white 
races  than  among  negroes.  In  the  negro's  skull  these  elevations  over 
the  roots  of  the  teeth  are  seldom  found  because  of  the  greater  thick- 
ness of  the  bone,  so  that  the  floor  of  the  sinus  in  the  negro  is  usually 


THE  ANTERIOR   WALL 


225 


snio(jLh.  The  (loor  is  coiu'axc  from  side  to  side  and  slii;hlly  .s(j  in  the 
anteroposterior  direc^lion,  as  illiistraled  in  Tiiis.  175,  200,  236  and  237, 
having  lluis  a  basin-like  form,  and  hein.u  iisualK'  below  the  lexcl  of  the 
nasal  ea\ity  (see  Fii^s.  295  and  297). 

The  Anterior  Wall. — The  anterior  wall  is  almost  a  square  with 
rounded  eorners.  ll  is  sm(K)th,  with  a  slight  depression,  whieh  varies 
aeeordin.u  to  the  position  of  the  i)assage  of  the  infra-orbital  eanal  or 
tube,   as  shown   in   Figs.  223  and  230.     OccasionalK-   the  ro(;ls  of  the 


Fig.  200. — Anterior  \'ie\v  of  a  \ertical  trans- 
verse bilateral  section  of  a  negro  skull,  showing 
a  deep  alveolar  process. 


Fig.   201. — Tooth   which  has   been  incorrectly 
drilled  through  while  in  the  mouth. 


canine  and  premolar  teeth  are  found  in  this  wall.  In  infancy  it  con- 
tains the  follicles  of  the  anterior  teeth  (see  Fig.  107).  The  anterior 
dental  canal,  for  the  accommodation  of  the  superior  alveolar  nerves  and 
vessels,  passes  from  the  sinus  into  the  wall  to  reach  the  anterior  teeth 
except  the  incisors  (see  Figs.  229  and  230).  The  reason  this  canal  is  so 
high  up  in  the  bone  is  that  the  apices  of  the  roots  of  the  teeth,  espe- 
cially the  canines,  before  eruption  or  during  development  and  growth, 
are  situated  high  in  the  bone.  As  the  teeth  descend  to  their  positions 
in  the  arch,  the  nerves  and  vessels  are  extended,  and  the  bony  tissue 

15 


220  THE  MAXILLARY  SINUS 

closes  around  them,  lea\ing  for  their  accommodation  a  canal  along  the 
track  traveled  by  the  teeth. 

The  Outer  Wall. — The  outer  wall  of  the  sinus  is  more  or  less 
triangular  and  concave  on  its  inner  surface;  the  concavity  may  extend 
into  the  zygomatic  bone  (see  Fig.  271).  The  wall  also  extends  upward 
and  outward  in  a  slightly  curved  manner.  The  surface  may  be  broken 
up  over  the  buccal  roots  of  the  teeth,  as  shown  Fig.  203.  The  plate 
of  bone  forming  the  outer  wall  varies  in  thickness  and  density  and 
undergoes  changes  in  this  particular  at  different  periods  of  life.  In 
childhood  the  dental  organs  of  the  upper  jaw,  before  eruption,  are 
located  in  the  outer  or  anterior  wall  or  in  the  floor  of  the  sinus. 
Fig.  195  demonstrates  the  relation  of  the  deciduous  teeth  to  the  floor 
of  the  sinus  at  the  location  of  the  molars.  A  little  later,  as  the  develop- 
ment of  the  permanent  teeth  proceeds,  and  they  are  pushed  forward 
preparatory^  to  taking  their  places  in  the  arch,  the  outer  and  lower 
portion  of  the  maxillary  bone  appears  to  be  crowded  with  teeth,  as 
shown  in  Fig.  107. 

The  Posterior  or  Zygomatic  Wall. — The  posterior  or  zygomatic 
wall  extends  from  a  line  vertical  to  the  centre  of  the  zygomatic  arch 
backward  and  inward  to  the  proximal  or  nasal  wall.  It  is  concave  in  a 
transverse  direction  and  nearly  straight  in  its  vertical  direction.  In 
youth  it  is  thick,  but,  like  the  outer  wall  of  the  sinus,  it  becomes 
thinner  as  age  advances,  until  it  may  be  no  thicker  than  a  sheet  of 
note-paper. 

The  Superior  Wall  or  Roof. — The  superior  wall  or  roof  of  the 
sinus  is  usually  triangular  in  shape,  the  base  of  the  triangle  being  at 
the  inner  or  nasal  wall.  It  is  convex  in  a  transverse  direction  with 
the  inner  edges  varying  in  height.  Its  junction  with  the  inner  wall 
varies  in  different  subjects.  Sometimes  it  is  found  on  the  level  of  the 
centre  of  the  floor  of  the  orbit  (see  Fig.  277).  At  other  times  it  is 
higher  and  near  the  centre  of  the  inner  orljital  wall  (see  Figs.  268  and 
298).  Its  surface  is  usually  marked  by  a  ridge  of  bone  which  contains 
the  groove  for  the  passage  of  the  infra-orbital  vessels  and  nerves.  This 
groove  commences  at  the  posterior  border  of  the  floor  of  the  orbit; 
continuing  forward,  it  is  lost  about  the  middle  of  the  floor,  where  it 


SEPTA   OF   Till:   MAXILLARY  SISUS  227 

passes  int(j  the-  infra-(>rl)ital  canal.  The  ridtic  ixttrds  downward  and 
forward  to  meet  the  anterior  wall  of  the  sinus.  The  dii)ping  down  of 
the  ridi;e  \  aries  grcalK  in  extinl,  bein.ii  scarcely  noticeable  in  s(jme 
specimens,  whili-  in  others  it  extends  so  far  that  the  canal  becomes 
distincth'  tubular  in  character,  passing  diagonally  through  the  sinus, 
carrying  the  infra-orbital  ner\c s  and  vessels  acnjss  the  anterior  jjortion, 
with  an  open  space  above  the  tube.  Ihc-  ojjen  sj)ace  above  the  sinus 
extends  outward  into  the  lower  rim  of  the  orbit,  forming  an  infra-orl)ital 
sinus  or  pocket,  a  variation  which  the  writer  has  mA  seen  mentioned  in 
any  work  on  anatomy.  The  tube-like  canal  has  a  thin  lamina  ot  bone 
extending  from  it  to  the  side  of  the  true  sinus.  For  the  above  charac- 
teristics see  Figs.  223,  230.  276,  277  and  361. 

The  Proximal  or  Nasal  Wall. — The  proximal  or  nasal  wall  of  the 
sinus  is  quadrangular  in  shape,  with  the  inferior  angles  slightly  rounded 
(see  Figs.  204  and  287).  In  a  typical  skull  this  wall  is  vertical  and 
slightly  convex.  The  lower  edge  almost  always  turns  slightly  outward 
to  join  the  floor  of  the  sinus,  but  occasionally  it  is  found  dipping  in 
under  the  floor  of  the  nasal  cavity  toward  the  median  line,  and 
meeting  the  floor  of  the  sinus  over  the  palatine  process  (see  Figs.  261, 
284  and  297). 

The  Ostium  Maxillare. — The  ostium  maxillare,  an  (nal-shaped 
foramen,  which  affords  communication  between  the  sinus  and  the 
nasal  cavity  through  the  hiatus  semilunaris,  is  usually  found  on  the 
upjxT  edge  of  the  proximal  wall  near  its  anterior  portion.  It  occa- 
sionally commences  in  the  roof  of  the  sinus,  then  passes  in  a  slightly 
curved  direction,  terminating  in  the  hiatus  semilunaris,  as  shown  in 
Figs.  279  and  280.  In  pathological  conditions  or  in  extreme  old  age, 
there  may  be  two  or  even  more  openings  between  the  maxillars-  sinus 
and  the  nasal  cavity  (see  Figs.  183,  184  and  186. 

Septa  of  the  Maxillary  Sinus. — The  shape  and  size  of  the  maxil- 
lars- sinus  and  the  character  of  its  partial  septa  vary  so  much  that  it  is 
almost  imj^ossible  to  say  what  is  its  typical  shajx^  and  what  are  its  typical 
septa.  From  whatever  direction  sections  are  made,  variations  in  shape 
and  size  will  be  found.  Partial  bony  or  membranous  septa  are  found 
passing  partly  across  in   \arious  directions,   but   the  writer  has  been 


228 


THE  MAXILLARY  SIX  US 


unable  to  find  complete  septa  of  the  maxillar}'  sinus,  though  it  is  said 
by  some  investigators  that  they  exist. 

Fig.  204  represents  an  anteroposterior  section  near  the  inner  wall  of 
the  orbit,  showing  a  maxillary  sinus  of  about  the  average  size  for  the 
age  of  the  subject.  A  portion  of  the  lumina  papyracea  or  os  planum 
is  cut  away  to  show  the  continuation  of  the  outlet  of  the  sinus.  A 
partial  bon)-  septum  arising  from  the  floor  and  passing  transversely 
across  forms  two  deep  pockets. 


/  ?ij^ 


i'  ■■  vy 


Fig.  202  Fig.  203 

Figs.  202  and  203. — Two  anteroposterior  sections  made  by  dividing  the  orbit  and  maxillary 
sinus  vertically,  showing  conical  elevations  over  the  roots  of  the  various  teeth.  The  root  of  the 
second  premolar  curves  forward.     It  more  commonly  curves  backward. 


Fig.  205  is  an  anterior  view  from  the  skull  of  an  old  person.  It 
shows  vertical  membranous  septa  of  different  sizes  on  the  two  sides, 
dividing  the  lower  portion  of  the  cavity  into  semi-chambers.  The 
septum  on  the  left  side  is  small;  that  on  the  right  extends  nearly  to 
the  roof.  Resorption  has  reduced  the  thickness  of  the  walls  of  the 
sinus. 

Fig.  206  is  from  an  anteroposterior  section  through  the  frontal 
sinus,   the  middle  of  the  orbit,   and  the  maxillary  sinus,  showing  an 


SEPTA   OF   THE  MAXILLARY  SLMS 


229 


Fig.  204. — Anteroposterior  division  through  the  maxillary  sinus. 


^      .tfT*— ^^, 


Fig.  205. — Anterior  view  of  a  vertical  transverse  section  from  a  skull  of  an  old  person,  showing  the 
thinness  of  the  walls  of  the  maxillary  sinus,  also  membranous  septa  of  the  sinus. 


230 


THE  MAXILLARY  SINUS 


incomplete  vertical  anteroposterior  membranous  septum  with  a  fora- 
men connecting  the  external  and  internal  compartments  of  the  sinus. 
Situated  on  the  membrane  are  a  number  of  small  osteophytes. 

Fig.  207  and  208  shows  what  at  first  sight  might  be  considered  to 
be  a  bony  division  of  the  maxillary  sinus;  but  close  investigation  reveals 
that  the  crescent-shaped  cavity  situated  on  the  upper  posterior  corner 
of  the  sinus  is  the  cell  of  the  orbital  process  of  the  palate  bone  cut  in 


Osteophytes  on  the 
septum 

Foramen  between  exter- 
nal and  internal 
chambers  of  sinus. 


Membranous  septum  of  sinus 

Fig.  206. — A  vertical  anteroposterior  division  through  the  frontal  sinus,  orbit,  and  maxillary  sinus, 

showing  a  partial  anteroposterior  membranous  septum  of  the  sinus. 


two.    A  probe  passed  through  the  opening  in  Fig.  208  would  enter  the 
superior  meatus  of  the  nose. 

Figs.  209  and  210  show  two  sections  of  a  negro's  face  through  the 
molar  teeth  and  the  middle  of  the  orbit.  A  sinus  ma^^  be  seen  at  the 
upper  posterior  corner  of  the  maxillary  sinus.  This  opens  into 
the  superior  meatus  of  the  nose  and  belongs  to  the  palate  bone.  The 
sinus  is  very  small. 


SEPTA   OF   rill:   MAXILLARY  SIMS 


231 


Figs.  211   and  212  art'  takiii   Iroiii   ihc  Icll  sick-  iA  aiKJlhcr  ncgn/s 
skull.     The  section  is  niadc  in  ihc  same  region  as  the  last,  showing  a 


Fig.  208 


Figs.  207  and  208. — Anteroposterior  division  through  the  centre  of  the  orbit,  maxillary  sinus,  and 
molar  teeth,  showing  a  crescent-shaped  cell  at  the  upper  posterior  corner  of  the  maxillary  sinus. 


Fk;.  209  Fui.  210 

Figs.  209  and  210. — Anteroposterior  division   through  the  centre  of  the  orbit,  maxillary  sinus,  and 
molar  teeth,  showing  a  triangular  cell  at  the  upper  posterior  corner  of  the  maxillary  sinus. 

very  small,  peculiarh'  shai)ed  sinus,  and  a  crescent-shaped  cell  which 
opens  into  the  superior  meatus. 


232 


THE  MAXILLARY  SINUS 


Figs.  213  and  2 14  are  from  the  right  side  of  the  same  skull  as  Figs.  211 
and  212,  showing  apparently  two  maxillary  sinuses.    The  posterior  one 


Fig.  211  Fig.  212 

Figs.  211  and  212. — Anteroposterior  division  through  the  centre  of  the  orbit,  maxillary  sinus,  and 
molar  teeth,  showing  a  peculiarly  shaped  sinus. 


Fig.  213  .  Fig.  214 

Figs.  213  and  214. — Anteroposterior  division  through  the  centre  of  the  orbit,  maxillary  sinus,  and 
teeth,  showing  an  enlarged  cell  of  the  orbital  process  of  the  palate  bone,  and  a  correspond ingty  small 
maxillary  sinus. 

passes  around  the  posterior  border  of  the  external  surface  of  the  anterior 
or  true  sinus.  The  apparent  second  sinus  is  undoubtedly  an  enlarged 
cell  of  the  orbital   process  of  the   palate  bone.     The  true  maxillary 


.S7!:/^7'.l    OF   Till-:  MAX/LL.IRV  SIX  US 


233 


sinus  is  cxtrcnicK'  small,  ll  may  be  ihal  on  account  of  this  the  cell 
was  abnormalh'  enlari>i'(l  lo  increase  the  air  space  of  this  region,  or 
that  the  palatal  process  has  encroached  upon  tln'  space  usually  occupied 
1)\  the  maxillary  bone.  The  bony  septum  of  this  specimen  might 
ver>'  easily  be  mistaken  as  dividing  the  sinus  into  two;  but  the 
writer  would  not  thus  classify  it,  as  this  posterior  sinus  opens  into  the 
superior  meatus,  as  do  the  other  palatal  cells  just  described. 

It  is  a  well-established  fact  that  the  maxillary  sinus  is  developed 
by  an  invagination  of  the  mucous  membrane  of  the  middle  meatus  into 
the  body  of  the  maxilla.  If  there  should  be  two  of  these  invaginations, 
it  could  then  be  easily  accepted  that  these  cells  are  a  divided  maxillary 


Fig.  216 


Figs.  215  and  216. — Anteroposterior  division  through  the  centre  of  the  orbit,  maxillary  sinus,  and 
molar  teeth,  showing  a  large  ma.xillary  sinus  and  a  large  sphenoidal  sinus. 

sinus;  but  as  the  outlet  of  the  posterior  one  is  into  the  superior  meatus, 
into  which  the  cells  of  the  orbital  process  of  the  palate  bone  open, 
it  seems  evident  that  this  is  an  enlarged  palatal  sinus  or  cell,  and  not  a 
divided  maxillary  sinus. 

Figs.  215  and  216  are  from  another  section  made  through  the  molar 
teeth  and  the  centre  of  the  orbit.  Posterior  to  the  maxillary  sinus 
we  find  another  sinus  of  a  different  character,  which,  from  superficial 
examination,  might  be  thought  to  be  related  to  it  or  to  be  an  enlarged 
cell  belonging  to  the  palate  bone,  a  probe  passed  into  it  leads  to  the 
supreme  or  fourth  meatus  of  the  nose,  indicating  that  it  may  be 
related  to  or  connected  with  the  sphenoidal  sinus.     In  fact,  it  is  a  very 


234 


THE  MAXILLARY  SIX  US 


large  sphenoidal  sinus  extending  out  laterally  in  a  line  almost  to  the 
outer  part  of  the  maxillary  bone. 

Figs.  217  and  218  are  an  outer  and  inner  view  of  a  section  showing  an 
extremel}'  large  sphenoidal  sinus.  The  cut  is  made  through  the  pre- 
molar teeth,  and  a  little  to  the  inner  side  of  the  middle  of  the  orbit, 
exposing  the  inner  wall  of  the  maxillary  sinus,  the  cell  of  the  palate 
bone,  and  the  sphenoidal  sinus,  over  which  is  seen  the  sella  turcica. 
The  irregular  opening  in  the  anterior  clinoid  process  in  Fig.  217  leads 
to  and  is  a  part  of  the  sphenoidal  sinus.  In  Fig.  218  the  external  wall 
of  the  nose  will  be  observed.     In  the  region  of  the  body  of  the  sphenoid 


Fig.  217  Fig.  218 

Figs.  217  and  218. — Two  views  of  an  anteroposterior  section.  Fig.  217  shows  the  inner  wall  of 
the  orbit,  maxillary  sinus,  and  openings  leading  into  the  sphenoidal  sinus.  Fig.  218  shows  the  lateral 
wall  of  the  nose  and  a  large  sphenoidal  sinus. 

bone  is  a  very  large  sinus,  at  the  bottom  of  which  will  be  noticed  a  space 
under  the  sella  turcica  shown  in  Fig.  217.  This  is  the  largest  sphenoidal 
sinus  which  has  come  under  the  observation  of  the  writer.  It  extends 
forward  to  the  cribriform  plate  of  the  ethmoid  bone;  backward  to 
near  the  basilar  process  of  the  occipital  bone;  laterally  on  a  line  with 
the  molar  teeth;  and  superiorly  into  the  anterior  clinoid  process,  with 
only  a  very  thin  plate  of  bone  between  it  and  the  floor  of  the  anterior 
fossa  of  the  brain-case.  In  such  cases  the  partition  between  the  sphe- 
noidal sinus  and  the  maxillary  sinus  is  so  thin  and  sieve-like  that 
infected  fluids  will  readily  find  their  way  from  the  former  to  the  latter. 


i)i:.\r.  1  /.  Ki:i.. 1 1  loxs/i/ps  235 

In  iIk'  usual  pliN  sioloiiical  dcscriplion  of  llic  sinus,  ihe  lluids  are 
spoken  of  as  passiiiL;  oul  of  it.  It  is  a  c|U('stion  if  this  l)e  the  case  under 
normal  conditions.  It  is  more  than  hkclx  that  the  law  ot  supi)h-  and 
demand  is  so  balanced  that  t/ic  parls  of  the  uuixillnry  sinus  are  kept 
moist  only,  the  openings  being  so  arranged  at  the  top  as  to  pre\ent  undue 
loss  of  the  fluids  while  the  subject  is  l>ing  on  the  back  or  is  standing. 
The  openings  in  the  other  air  cells  or  sinuses  are  so  arranged  as  to  make 
almost  comj^Iete  drainage  through  their  most  dependent  parts. 

Dental  Relationships. — Because  of  the  close  anatomical  relation 
of  the  nia.\illar\'  sinus  with  the  tooth-germs  and  the  roots  of  the  jier- 
manent  teeth,  it  is  evident  that  the  sinus  must  l)e  more  or  less  influenced 
by  them.  As  the  teeth  develop  and  descend  into  their  normal  i)laces, 
the  sinus  increases  in  size.  If  a  tooth  situated  near  the  sinus  be  retarded 
in  its  eruption,  the  development  of  the  sinus  is  interfered  with  at 
that  particular  point.  If  the  root  of  a  tooth  be  left  in  the  jaw  in  old 
age,  resorption  immediately  over  that  root  will  not  progress  as  in  the 
parts  from  which  the  roots  have  been  removed  (see  Fig.  287). 

It  has  been  shown  how  closely  the  apical  portions  of  the  roots  of 
the  teeth  are  often  associated  with  the  sinus  (see  Figs.  196,  197,  199, 
202,  and  203).  This  close  proximity  gives  the  impression  that  the 
maxillary  sinus  is  more  often  infected  from  diseased  teeth  than  from  any 
other  source,  some  authorities  claiming  that  three-fifths  of  the  diseases 
of  the  sinus  are  brought  about  in  that  way.  The  writer  thinks  this 
a  mistake.  Though  recognizing  that  diseases  of  the  sinus  do  arise 
from  the  teeth,  he  believes  that,  aside  from  constitutional  diseases 
and  malformations,  it  is  more  often  through  the  common  communica- 
tion between  the  nasal  cavity,  the  frontal  sinuses,  and  the  ethmoid 
cells,  that  infection  is  conveyed  to  the  maxillary  sinus  from  diseased 
cells  and  sinuses  above  it.  He  recognizes,  at  the  same  time,  that  the 
posterior  ethmoidal  and  sphenoidal  cells  and  the  cells  of  the  orbital 
process  of  the  j)alate  bone  can  also  infect  the  sinus  by  resorption  of 
the  partition  between  these  cavities.  It  is  the  writer's  observation 
that  there  are  more  cases  in  which  teeth  are  lost  through  diseases 
of  the  sinus  than  cases  in  which  the  teeth  are  primarih  diseased, 
causing   infection   of   the   sinus   and  associated  cells.      In   Fig.    197   it 


236 


THE  MAXILLARY  SINUS 


will    be    observed  that    the   anterior  buccal  and  palatal  roots  of  the 
first  molar  tooth  pass  up   into    the  walls   of   the   sinus.    This  is   the 


Fig.  219 


Fig.  220 
Figs.  219  and  220.— Anteroposterior  division  through  the  orbit,  frontal  and  maxillary  sinuses, 
and  molar  teeth,  showing  an  undeveloped  molar  which  was  causing  irritation  in  the  floor  of  the 
sinus. 


DENT.  1  /,  REI.A  TIOXSIIIPS  237 

class  of  cases  where  diseased  leelh  may  cause  inteclion  (A  tlie  max- 
illary sinus.  If  the  i)uli)  of  a  tootli  so  related  to  the  sinus  sh(juld 
become  devitalized  and  iufecled.  ihe  i)arts  around  the  apical  foramen 
might  also  become  infected  and  abscesses  occur.  PVom  the  close  prox- 
imity of  the  points  of  the  roots  to  the  sinus,  it  might  be  supposed  that 
these  abscesses  would  l)reak  into  it,  as  they  occasionally  do.  Other 
examples  of  infection  through  diseased  teeth  in  no  way  militate  against 
the  idea  that  the  teeth  are  not  first  in  importance  as  factors  in  causing 
disease  of  the  sinuses. 

It  is,  however,  clear  that  pus  or  infected  matter  will  pass  in  the 
direction  of  the  least  resistance.  When  the  investing  tissues  of  a  tooth 
become  so  infected,  the  osteogenetic  function  of  this  region  is  to  stimu- 
late renewed  activity,  with  the  result  that  a  new  layer  of  bone  is  pro- 
duced which  covers  these  parts  and  protects  this  cavity,  so  that 
abscesses,  with  but  few  exceptions,  point  and  break  into  the  mouth. 

Careless  operation  by  the  dentist  sometimes  causes  infection  of 
the  sinus,  as  drilling  through  the  tooth  and  the  floor  of  the  sinus,  or 
forcing  the  root  of  a  tooth  into  the  sinus,  through  fracture  of  the  wall 
in  an  unskilful  effort  to  extract,  or  carelessness  in  driving  artificial 
crowns  or  bridges  upon  the  teeth  or  roots. 

Figs.  219  and  220  are  views  of  an  undeveloped  and  unerupted 
third  molar  which  was  causing  irritation  in  the  floor  of  the  sinus. 

Figs.  221  and  222  are  from  the  opposite  side  of  the  same  skull, 
showing  a  similar  condition  and  with  an  abscess  which  has  burrowed 
under  the  mucous  membrane  near  the  roots  of  the  first  molar  tooth. 

Figs.  223  and  224  are  views  of  an  anteroposterior  section  of  the  upper 
jaw  with  the  first  molar  decayed  and  the  pulp-chamber  of  the  tooth 
open.  The  root-canal  has  been  infected  and  the  infection  has  been 
carried  into  the  sinus.  In  this  case  there  is  evidence  of  a  productive 
periostitis  upon  the  floor  of  the  sinus,  which  has  caused  a  thickening 
of  bone  over  the  apex  of  the  root.  At  a  later  period  suppurative  inflam- 
mation has  occurred  and  perforated  the  floor. 

Fig.  225  is  a  view  of  the  floor  of  the  sinus  and  the  nasal  cavity. 
In  the  middle  of  the  sinus  there  is  a  conical  elevation  with  an  opening 
in  the  centre  exposing  the  apex  of  a  tooth.     In  this  case  new  bone  has 


238 


THE  MAXILLARY  SIX  US 


been  formed  over  the  diseased  root,  but  at  some  subsequent  time  the 
bone  has  been  broken  down  and  the  sinus  has  become  infected. 


Fig.  221 


Fig.  222 
Figs.  221  and  222. — Anteroposterior  division  through  the  orbit,  frontal  sinus,  maxillary  sinus, 
and  molar  teeth,  showing  a  similar  condition  as  in  Figs.  219  and  220.    An  abscess  has  burrowed  under 
the  mucous  membrane  near  the  roots  of  the  first  molar  tooth. 


Fig.  226  is  a  vertical  transverse  section  of  the  sinuses  and  nasal 
cavity.  in  the  floor  of  the  right  sinus  the  conical  portion  of  the 
bone,   covering  the  infected   tooth,   has  been   cut   through  its  centre, 


DENTAL  RELAT  ION  SHIPS 


239 


exposing:  the  cmuI  of  tlu-  root  in  the  inl\(lc(l  ntiioii,  tlu-  coiulilicjii  being 
somcwhal  similar  to  those  siiow  n  in  I''ii;s.  22^  and  225. 


Infra-orbital  sinus_j'""  ■ 

\ 
Infra-orbital  forainoii — ■, 


Sound  passing  through 

infra-orbital  canal 

and  foramen 


Maxillary  sinus 


Opening  caused  by  apica 
abscess 


Fig.  223 


— Infra-orbital  sinus 
-—  Opening  into  zygomatic  bone 


Fii;.   224 
Figs.  223  and  224. — Anteroposterior  division  of  the  maxilla,  showing  opening  of  a  dental  abscess 
within  the  maxillary  sinus  and  an  infra-orbital  sinus. 

Figs.  227  and  228  was  made  from  the  left  maxilla  of  the  same  skull 
from  which  Figs.  223  and  224  were  taken.  The  pulj)  of  the  first  molar 
was  devitalized.      In  228  an  enlargement  of  the  infected  root  is  seen. 


240 


THE  MAXILLARY  SINUS 

Floor  of  the   nasal  cavity 


Apical  foramen  of  tooth 
Floor  of  maxillary  sinus 


Fig,  225. — Horizontal  section  above  the  right  floor  of  the  nasal  cavity  and  maxillary  sinus,  showing 
the  opening  of  a  dental  abscess  in  the  floor. 


Portion  of  eye 


Cell  in  the 
middle  concha 


Orbit 


Middle  concha 

Middle  meatus 
axillary  sinus 


Fig.  226. — Anterior  view  of  a  vertical  transverse  section  in  the  region  of  the  crista  galli,  middle  of 
orbit,  and  molar  teeth,  showing  effect  of  dental  abscess  in  floor  of  maxillary  sinus. 


DENT  A  L  RELA  TION  SHIPS 


241 


An  exaniiiialion  of  the  hard   i)alatL'   shows  that  the  discharge  of   the 
abscess  was  made  into   the  moulh,  which  the  writer  beheves  is  the 


Fig.  227 


Fig.  228 


/•■  M  S 


Figs.  227  and  228. — Horizontal  sections  through  the  maxillary  sinus.  F  M  S,  floor  of  the  max- 
illary sinus.  In  Fig.  228  there  is  an  exostosis  over  the  position  of  an  infected  root  of  the  first  molar 
tooth.  In  Fig.  227  the  cap  of  bone  covering  the  root  has  been  removed,  exposing  the  end  of  the  root 
and  a  fistula  extending  downward,  opening  into  the  roof  of  the  mouth. 


Incisive  canal 


Fig.  229. — Alveolar  process. 

usual  outlet  for  apical  abscesses  in  the  upper  jaw — of  course  recognizing 
that  they  occasionalh-  oj^en  into  the  sinus. 

IG 


242 


THE  MAXILLARY  SIX  US 


The  vessels  of  nourishment  to  the  maxillary  teeth  do  not  pass 
through  and  along  a  canal  in  the  cancellated  tissue  as  they  do  in  the 
mandible,  but  in  a  groove  on  the  outer  wall  of  the  maxillary  sinus  (as 
shown  in  Fig.  230),  from  which  are  given  off  branches  to  the  apices 
of  the  roots  of  the  teeth,  many  of  the  latter  being  covered  with  only  a 
thin  plate  of  bone.  It  is  through  the  vessels  of  this  region  that  infec- 
tion can  be  conveyed  from  the  teeth  and  alveolar  process  to  the 
maxillary  sinuses  or  vice  versa. 

It  has  been  shown  by  these  examples  how  numerous  are  the  varia- 
tions of  the  maxillary  sinus  in  shape,  size,  and  position,  and  in  its  rela- 


Groove  for  alveolar 
nerve  and  vessels 


Sound  passed  through  infra-orbital 
canal  and  foramen 


Fig.  230. — Anteroposterior  division  through  the  maxillary  sinus  and  the  teeth,  showing  an 

infra-orbital  sinus  above  the  canal. 


tion  to  the  mouth  and  teeth,  the  nasal  cavity,  the  frontal  sinus,  the 
ethmoidal  cells,  the  cell  of  the  orbital  process  of  the  palate  bone,  and 
the  sphenoidal  sinus.  The  variations  are  most  important  to  the  dentist 
and  rhinologist.  In  the  field  of  oral  surgery,  so  many  complications 
often  arise  in  the  extraction  and  treatment  of  teeth  that  a  thoroughly 
scientific  knowledge  of  the  results  of  all  recent  research  in  this  region 
is  absolutely  necessary. 

Surgical  Relations. — In  the  extraction  of  the  upper  molar  teeth 
great  care  should  be  exercised,  because,  as  has  been  shown,  where 
the    sinus    is    large,   extending    downward    and    inward    between    the 


SURGICA  L   REL.  1  TIONS 


243 


roots  of  I  he  (ccth,  as  seen  in  Fi^.  199,  if  undue  f(jrce  slioukl  be 
exerted,  not  onK  the  looth  grasi)ed  by  the  forceps,  but  also  a  great 
portion  of  the  lloor  with  other  teeth  attaclied  is  hable  to  be  carried 
away.  M\anij)les  of  tlie  results  of  sueh  accidents  are  shown  in 
Figs.  231,  232  and  2^^^.  Figs.  231  and  232  are  from  specMmens 
broken  away  with  the  ordinary  forceps,  and  Fig.  233  is  from  a 
specimen  of  the  work  of  the  old-fashioned  turnkey.  When  using  much 
force  in  placnng  artificial  bridges  or  crowns  upon  the  teeth  immediately 
beneath  the  sinus,  there  is  danger  of  breaking  the  floor  in  subjects 
where  the  walls  are  thin.  When  the  pulps  of  the  teeth  have  become 
diseased  and  infected,  the  infection  may  pass  out  of  the  apical  foramen 


■y/  / 


Fig.  231  Fig.  232  Fig.  233 

Figs.  231,  232  and  233. — Three  pieces  of  bone  with  molar  teeth  that  have  been  accidentally 
broken  away  with  part  of  the  floor  of  the  maxillary  sinus  in  extraction;  Figs.  231  and  232  with  ordinary 
forceps,  Fig.  233  with  an  old-fashioned  turnkey. 


into  the  tissues  immediately  surrounding  the  root,  and  thence  into 
the  sinus,  as  has  before  been  mentioned.  In  cleansing  the  root- 
canal  there  is  some  danger  of  passing  the  instrument  through  the  apical 
foramen  directly  into  the  sinus.  Certain  diseases  of  the  teeth  caused 
by  inflammation  of  the  jDcriodontal  membrane  with  abscesses  threaten- 
ing to  open  into  the  mouth,  sometimes  disappear  suddenly,  although 
no  fistulous  opening  into  the  mouth  has  formed.  When  this  occurs 
an  abscess  has  frequently  found  an  opening  into  the  sinus.  Diseases 
of  the  maxillary  sinus  are  liable  to  produce  disturbances  in  the  teeth> 
as  their  blood  supply  passes  along  the  floor  of  the  sinus  and  through 
the  wall.  Branches  of  the  trigeminal  nerve  accompany  the  vessels,  and 
these  also  are  liable  to  become  deranged  functionally. 


244  THE  MAXILLARY  SIXUS 

The  maxillar}-  sinus  is  on  a  lower  plane  than  any  of  the  other 
sinuses  and  cells  associated  with  the  nasal  cavity,  and  has  its  outlet 
in  the  upper  anterior  portion;  when  the  hiatus  semilunaris  is  blocked 
below  or  posterior  to  the  opening  of  the  sinus,  it  becomes  engorged 
with  the  fluids  which  have  no  other  normal  exit,  thus  producing  pres- 
sure upon  its  walls  and  upon  the  nerves  and  vessels  passing  through  it. 
It  is  in  such  cases  that  additional  openings  are  found  leading  from  the 
maxillary  sinus  (see  Figs.  183,  184,  185,  186,  187  and  188). 

Pathological  Conditions. — Pathological  conditions  of  the  maxil- 
lary sinus  vary  in  almost  every  aspect,  and  arise  from  a  great  diversity 
of  causes,  of  which,  may  be  mentioned: 

(i)  Pathological  conditions  of  the  parents  of  the  child  at  time  of 
conception. 

If  either  parent  should  have  any  constitutional  disease  which 
could  be  transmitted  to  the  offspring,  or  if  a  parent  should  have  an 
abnormally-shaped  face  such  as  compressed  dental  arches,  narrow 
nasal  cavities,  irregularities  of 'the  pneumatic  spaces,  etc.,  the  child 
would  begin  its  existence  with  a  strong  predisposing  cause  for  patho- 
logical conditions  which  might  continue  throughout  life. 

(2)  Constitutional  disturbances  during  the  growth  and  develop- 
ment of  the  child. 

Among  the  general  constitutional  disturbances  that  predispose 
to  pathological  conditions  of  the  sinus  are  syphilis,  the  acute  exan- 
themata, as  scarlet  fever  and  measles,  and  disorders  of  nutrition,  as 
rickets,  etc. ;  also  local  disturbances,  as  infected  or  enlarged  tonsils, 
adenoids,  nasal  polypi,  or  anything  else  that  tends  to  obstruct  or  close 
the  nasal  passages,  thus  shutting  off  proper  breathing  spaces,  drainage, 
and  ventilation.  These  conditions  should  all  be  taken  into  considera- 
tion when  studying  the  pathology  and  treatment  of  the  maxillar}^  sinus. 

(3)  Infection  by  continuity  from  the  nasal  mucosa. 

This  is  one  of  the  most  frequent  sources  by  which  a  pathological 
condition  of  the  maxillary  sinus  is  brought  about,  the  severity  of  the 
condition  depending  upon  the  character  and  quality  of  the  infected 
matter  transmitted.  The  maxillary  sinus,  like  all  open  cavities  which 
arc  covered  with  epithelium,  is  immune  to  infection  to  a  great  extent, 


PAT  no  LOGICAL  LUMJJTIU.WS  245 

but  repealed  or  cH)nslant  e\i)()sure  lo  infected  mailer  will  finalK'  result 
in  a  diseased  eondilicju,  prcKlucinj;  a  discharge  of  the  l>'pe  of  the  par- 
lirular  miero()rji:anisms  introduced.  Therefore  anylhinji:  that  affects 
the  mucosa  of  the  nose  will  ha\'e  its  influence  1)\'  direct  action  upon 
all  the  associated  i)neuniatic  splices.  The  effect  of  an  ordinary-  cold 
may  not  reach  the  sinus,  but  if  the  patient  suffers  from  repeated 
coryza  continued  for  long  periods,  it  will  be  affected  finally  and  remain 
vSO  even  after  the  membrane  of  the  nose  has  recovered;  because  when 
the  ciliated  epithelium  of  the  sinus  becomes  diseased,  it  has  not  the 
power  to  convey  the  infection  and  broken-down  tissue  ujnvard  to  the 
natural  outlet. 

(4)  Infection  through  the  l)lo(jd  supply. 

The  blood  sui)i)h'  of  the  greater  portion  of  the  sinus  comes  from  the 
same  source  as  that  of  the  teeth,  namely,  the  superior  alveolar  artery-, 
which  gives  off  small  branches  to  the  teeth,  the  alveolar  process  and 
the  greater  portion  of  the  mucous  membrane  of  the  sinus.  The  veins 
which  commence  in  the  alveolar  process,  the  teeth  and  the  mucous 
membrane  of  the  sinus,  anastomose  quite  freely  with  one  another. 
A  similar  arrangement  of  the  bloodvessels  exists  in  the  region  of  the 
outlet  of  the  sinus  into  the  nose.  Consequently  it  will  be  seen  that 
infection  from  one  region  will  easily  be  carried  throughout  all  the  area 
ha\  ing  the  same  blood  supply.  If  the  frontal  sinuses  or  ethmoidal 
cells  become  diseased,  fluids  may  be  diverted  into  the  maxillary  sinus, 
which  will  in  turn  become  infected.  Again,  if  the  sinus  should  become 
infected  through  the  blood  supply  to  the  mucous  membrane  which 
receives  its  nourishment  through  various  vessels,  or  if  the  mucous 
membrane  should  become  infected  through  diseased  teeth  or  osteo- 
myelitis or  any  other  sourse,  the  infection  produced  would  pass  from 
the  maxillary  sinus  to  the  frontal  sinus,  the  ethmoidal  cells  and  tissues 
in  close  relation  to  those  parts.  There  are  but  few  cases  of  osteomyelitis 
on  record  arising  from  the  walls  of  the  maxillary  sinus  per  se. 

(5)  Foreign  bodies  are  occasionally  found  in  the  sinus  which  pro- 
duce a  ])athological  condition.  They  are  usually  discovered  in  cases 
where  the  sinus  has  been  previously  diseased  and  treated. 


246  THE  MAXILLARY  SINUS 

(6)  Cysts,  pol^'pi,  impacted  or  misplaced  teeth,  odontomata, 
osteophytes,  mahgnant  and  benign  tumors  are  strong  predisposing 
factors  toward  pathological  conditions  of  the  sinus,  and  should  be 
carcfulh"  considered  in  all  diagnoses  of  sinus  troubles,  especially  as 
cysts  and  tumors  of  this  region  are  more  or  less  obscure  in  their  incipi- 
ency.  Impacted  or  deflected  teeth  are  also  often  difficult  to  diagnose, 
if  one  be  not  thoroughly  familiar  with  the  variations  in  the  anatomy 
of  the  parts,  or  if  a  thorough  radiographic  inspection  be  omitted. 

Treatment  of  Pathological  Conditions  of  the  Maxillary  Sinus. — As 
the  causes  of  pathological  conditions  of  the  maxillary  sinus  are  so 
various,  it  is  evident  that  etiology,  diagnosis  and  treatment  must 
cover  a  wide  range.  The  principal  thing  is  to  make  a  correct  diagnosis 
and  study  of  the  etiology,  and  when  such  is  obtained,  on  general 
principles,  the  treatment  should  be  to  remove  the  cause,  whether  it 
be  from  constitutional  disturbances,  diseased  teeth,  necrosis  of  the 
bone,  impacted  teeth,  odontomata,  dental  or  other  cysts,  polypi,  new 
growths,  malignant  or  benign,  foreign  bodies,  diseases  communicated 
through  the  circulation,  from  adjacent  parts  that  are  pathological, 
direct  infections  from  other  pneumatic  spaces,  or  from  any  diseases 
associated  with  the  nasal  cavity. 

All  diseases  of  the  maxillary  sinus  that  are  caused  by  the  teeth, 
or  any  diseases  of  its  walls,  except  the  nasal,  should  be  treated  through 
the  mouth,  this  usually  avoids  the  contamination  of  the  nasal  cavity 
and  its  associated  parts.  On  general  principles,  all  diseases  of  the 
maxillary  sinus  caused  by  diseases  of  the  nasal  side  of  its  walls  should 
be  treated  from  the  nasal  standpoint. 

Occasionally  where  a  pathological  condition  originates  in  the  nasal 
region  and  is  treated  and  cured,  the  sinus  may  become  infected  and 
remain  diseased,  in  such  cases  treatment  through  the  mouth  is  more 
appropriate  than  through  the  nose. 

When  the  maxillary  sinuses  have  complicated  septa  creating  pockets 
inaccessable  through  the  nasal  cavity  (see  Fig.  295),  or  in  cases  where 
the  maxillary  sinuses  extend  downward  far  below  the  level  of  the  nasal 
floor  (Figs.  284  and  297),  treatment  may  have  to  be  undertaken 
through  the  mouth. 


TREATMEXTOr  PATHOLOGICAL  COX D/TKKXS  OL  MAXILLARY  SIXCS    2A1 

If  Figs.  276  and  277  hv  cxaniiiu'd  {\\vy  will  give  illustrations  of 
pockets  and  anatomical  conditions  of  the  maxillary  sinus  that  would 
make  it  most  diHicuIl  to  treat  esjx'cialK  if  it  should  be  required  lo 
curette  the  parts.  An  infra-orbital  sinus  ma\'  be  seen  under  the  outer 
and  anterior  portion  of  the  floor  of  the  orbit;  in  case  of  disease  of  this 
sinus  it  would  be  most  difticult  to  reach  through  the  nasal  cavity.  In 
Fig.  287  there  are  two  deej)  pockets  that  would  be  difficult  to  reach 
through  the  nasal  ca\it\',  while  through  the  alveolar  i^rocess  it  would 
be  comparatively  easy  and  would  avoid  the  interfering  with  the  nose. 

Figs.  284  and  297  show  cases  where  the  floors  of  the  maxillary 
sinuses  are  far  l)elow  the  level  of  that  of  the  nasal  cavity. 

An  ordinary  opening  into  the  maxillary  sinus  through  the  mouth 
heals  u])  \ery  (juickly,  especialh'  if  the  disease  of  the  sinus  becomes 
cured,  which  is  usually  accomplished  if  the  trouble  has  been  caused 
by  diseased  teeth. 


CHAPTER    IX. 
THE  FRONTAL  SINUS. 

The  frontal  sinuses  are  usually  two  irregular-shaped  cavities  sit- 
uated in  the  lower  part  of  the  facial  portion  of  the  frontal  bone  and 
in  the  process  forming  the  roofs  of  the  orbits,  with  a  thin  lamina  of 
bone  between  them.  They  var^'  considerably  in  size,  shape,  position, 
and  number. 

Development. — They  appear  about  the  second  year  after  birth 
and  are  formed  by  an  invagination  from  the  upper  anterior  portion 
of  the  hiatus  semilunaris  and  by  a  dissolution  of  the  tissue  between 
the  outer  and  inner  plates  of  the  frontal  bone,  the  excavations  for  the 
formation  of  these  sinuses  as  well  as  for  the  various  other  cells  and 
sinuses  being  carried  on  through  the  agency  of  the  osteoclasts.  The 
sinuses  continue  to  increase  in  size  as  age  advances.  They  are  lined 
with  mucous  membrane  and  communicate  with  the  nasal  cavities 
through  the  infundibulum  and  the  hiatus  semilunaris.  There  are 
skulls  in  which  frontal  sinuses  do  not  exist;  there  are  other  skulls  in 
which  there  is  but  one  sinus  that  may  be  very  small,  or  it  may  extend 
from  one  of  the  external  angular  processes  beyond  the  medial  line  of 
the  frontal  bone  and  upward  to  a  point  above  the  level  of  the  frontal 
eminences  or  posteriorly  over  the  orbit  almost  to  the  optic  foramen. 
It  sometimes  spreads  outward  and  backward  terminating  in  the  great 
wing  of  the  sphenoid  bone;  it  may  be  found  not  only  in  the  ascending 
portion  of  the  bone,  l^ut  extending  downward  and  backward  may 
become  one  common  cavity  with  the  anterior  ethmoid  cells  and  the  max- 
illary sinus  (see  Figs.  247  and  296) .  There  arc  usually  two  frontal  sinuses, 
each  having  an  independent  outlet  into  the  nasal  cavities,  but  specimens 
exist  in  which  three  or  more  sinuses  are  present,  all  in  the  ascending 
portion  of  the  bone  and  each  having  its  independent  outlet.  The 
portions   which    f)ass    (jver    the    orbit    might    be  called    supra-orbital 


DEVELOPMENT 


249 


sinuses,  cspccialK'  if  i1k'>-  have  complete  partiticjns  and  outlets  (jther 
than  the  one  which  occupies  the  ascendinj^  portion  of  the  bone. 

Figs,  234  and  235  show  a  large  left  frontal  sinus,  wJiich  passes  over 
to  the  right  of  the  medial  line,  leaving  but  little  room  for  the  right 
sinus  in  its  normal  position,  as  is  seen  in  Fig.  235.  Often,  in  such 
cases,  the  opposite  side  will  extend  its  air  space  in  some  other  direction 
to  make  up  for  the  loss  caused  by  the  invasion. 


Fr;.  234  Fig.  235 

Figs.  234  and  235. — Lateral  walls  of  the  nasal  cavity,  showing  the  left  frontal  sinus  extended  over 

to  the  right  of  the  medial  line. 

Figs.  236  and  237  are  made  from  Fig.  235,  cut  through  the  centre 
of  the  orbit,  showing  that  the  frontal  sinus  has  extended  back  over 
the  orbit  to  the  region  of  the  optic  foramen.  It  has  also  extended 
outward  under  the  zygomatic  process  of  the  frontal  bone. 

Figs.  238  and  239  are  made  from  a  skull  where  the  frontal  sinus 
has  extended  upward  under  the  region  of  the  frontal  eminence  and 
downward  to  the  middle  of  the  orbit  or  almost  on  a  level  with  the 
upper  portion  of  the  maxillary  sinus. 

Fig.  240  is  an  illustration  of  two  large  frontal  sinuses,  extending 
from  one  zygomatic  process  of  the  frontal  bone  to  the  other,  with 
but  a  thin  complete  septum  between.  This  septum  is  not  in  the 
centre,  but  is  carried  over  the  left  side.  The  sinuses  pass  backward 
over  the  greater  portion  of  the  orbits,  and  upward  toward  the  frontal 


250 


THE  FRONTAL  SINUS 


eminence.  There  is  quite  a  depression  over  the  frontal  crest,  which 
is  very  large  in  this  specimen.  There  are  also  several  partial  septa 
runninQ-  in  various  directions  in  the  two  sinuses. 


Fig.  236 


Fig.  237 


Figs.  236  and  237. — Two  anteroposterior  sections  (made  from  Fig.  170)  through  the  frontal 
sinus,  centre  of  orbit,  maxillary  sinus,  and  cell  of  the  orbital  process  of  the  palate  bone,  showing  the 
frontal  sinus  extending  backward  over  the  orbit  to  the  region  of  the  optic  foramen.  It  also  extends 
under  the  zygomatic  process  of  the  frontal  bone. 


Fig.  238 


Fig.  239 


Figs.  238  and  239. — Two  vertical  transverse  sections  through  the  frontal  sinu.ses  and  nasal  cavities, 
showing  the  frontal  sinus  extending  below  the  level  of  the  middle  of  the  orbit. 


DEVELOPMEXT 


251 


OccasionalK-  llu-  fnjiUal  sinus  extends  into  the  crista  ijalli  form- 
ing a  cell  in  that  i)rocess  (see  Figs.  269,  281,  282,  292,  293,  294.  295 
and  296). 


Fig.  240. — Large  frontal  sinuses  extending  from  one  zygomatic  process  of  the  frontal  bone  to 

the  other. 


Fig.  241. — Two  sections  of  th:?  supra-orbital  region,  showing  no  frontal  sinus. 

Fig.  241  is  made  from  two  sections  taken  from  the  supra-orbital 
region  of  the  skull.  The  upper  figure  shows  that  the  anterior  portion 
of  the  frontal  bone  has  been  removed  from  the  region  of  the  super- 
ciliary ridges,  exhibiting  no  indication  of  the  sinus  in  the  ascending 


252 


THE  FRONTAL  SINUS 


portion  of  the  frontal  bone.  The  lower  picture  shows  no  evidence  of 
the  sinuses  passing  into  the  horizontal  portion  or  over  the  orbits. 

Fig.  242  is  made  from  a  specimen  having  only  a  right  frontal 
sinus,  which  extends  unbroken  far  over  to  the  left.  This  sinus  passes 
partly  over  the  orbit  and  has  but  one  outlet. 

Fig.  243  shows  two  rather  typical  frontal  sinuses  with  two  outlets 
and  a  complete  septum  near  the  medial  line.  There  is  also  one  par- 
tial septum  near  the  medial  line,  and  one  partial  septum  in  each 
sinus  forming  two  pockets  near  the  zygomatic  process.  The  right 
sinus  measures  horizontally  35  mm.,  the  left  30  mm.;  the  depth  of 
the  right  sinus  is  42  mm.  and  the  left  35  mm. 


Fig.  242. — Anterior    view   of   skull   with  bone 
removed,  exposing  only  one  frontal  sinus. 


Fig.  243. — Anterior  view,  showing  two  frontal 
sinuses. 


Fig.  244  shows  three  complete  frontal  sinuses  with  three  individual 
outlets  and  two  complete  septa.  The  two  lateral  sinuses  pass  back- 
ward well  over  the  orbits. 

Fig.  245  is  made  from  a  skull  that  has  four  frontal  sinuses,  with 
four  independent  outlets  and  three  complete  septa.  Some  writers 
would  class  the  two  middle  sinuses  as  anterior  ethmoidal  cells  which 
had  invaded  the  frontal  bone.  If  these  cells  should  exist  without  the 
two  larger  sinuses  they  would  then  be  called  frontal  sinuses  by  these 
same  writers. 


DEVELOPMKXT 


253 


Fii^.  246  is  made  from  a  specimen  containing  five  frontal  sinuses 
and  having  four  complete  septa.  Four  of  the  sinuses  extend  well 
upward   to  about    the  same  height. 


Fig.  244. — Anterior  yww,  showing  three  frontal  sinus 


Fig.  245.— Anterior  view,  showing  four  frontal         Fig.  246.— Anterior  view,  showing  five  frontal 


254 


THE  FRONTAL  SINUS 


Fig.  247  is  a  posterior  view  made  from  a  specimen  having  two  large 
frontal  sinuses  with  a  complete  septum.  The  right  sinus  extends  back 
over  the  orbit  and  down  through  the  region  of  the  anterior  ethmoidal 
cell,  continuing  into  the  maxillary  sinus  and  making  one  common 
cavity  of  the  frontal  sinus,  the  anterior  ethmoidal  cells  and  the  maxil- 
lary sinus. 

Fig.  248  is  made  from  a  skull  having  two  large  frontal  sinuses. 
There  appear  to  be  three  sinuses  in  the  picture,  but  the  septum  on 


Fig.  247. — Posterior  views,  showing  two 
large  maxillary  sinuses.  The  right  one  forming 
a  common  cavity  with  ethmoid  cell  and  maxil- 
lary sinuses. 


Fig.  248. — Anterior  view,  showing  two 
frontal  sinuses,  the  right  one  very  large  ex- 
tending well  over  to  the  left  side. 


the  right  is  incomplete,  making  but  one  sinus  on  that  side,  which 
is  very  large,  extending  from  the  right  zygomatic  process  trans- 
versely well  over  to  the  left  side,  and  measuring  65  mm.  Its  depth 
from  the  top  to  the  outlet  is  45  mm.,  and  it  extends  well  back  over 
the  orbit  40  mm. ;  the  left  sinus  passes  outward  and  backward  to  about 
one-half  the  distance  of  that  on  the  right  side. 

Fig.  249,  from  a  horizontal  section  above  the  orbit,  shows  a  trans- 
verse section  of  a  large  left  frontal  sinus,  measuring  67  mm.  from  the 
left    zygomatic    process  to   a  position   over   the  centre  of    the  right 


niAl'.LOl'MENT 


255 


iiifra-()rl)ilal  loranien,  willuHil  a  scplimi.  The  ri^lit  Ironlal  siiuis,  meas- 
urinii  40  iiini.,  has  several  small  inccjmplete,  nearly  horizontal  septa, 
making  a  numhiM-  of  horizontal  jKJckets. 

Fig.  250  is  made  from  a  transverse  section  of  the  face  with  a 
l)ortion  of  the  bone  removed  to  expose  the  frontal  sinuses.  The 
right  sinus  is  extremely  large,  extending  from  the  right  zygomatic 
process  over  toward  the  left  and  measuring  67  mm.,  leaving  but  a 
slight  space  for  the  left  frontal  sinus,  which  measures  15  mm.     The 


Fig.  249. — Horizontal  section  above  the  orbit. 


Fig.  250. — Anterior  view,  showing  a 
large  right  frontal  sinus,  the  left  sinus 
is  very  small. 


septum  between  these  sinuses  has  an  inclination  of  about  45  degrees. 
The  right  sinus  also  extends  well  back  over  the  orbit  and  into  the 
crista  galli. 

Fig.  251  is  made  from  a  transverse  section  of  the  face  with  a  por- 
tion of  the  bone  removed,  showing  two  ver\'  large  frontal  sinuses 
which  extend  backward  over  the  orbits,  where  they  are  divided  b\- 
several  incomplete  sejDta.  They  also  extend  downward  and  communi- 
cate directly  with  the  maxillary  sinuses.  The  right  and  left  sinuses 
measure  horizontally  50  mm.  and  their  depth  is  40  mm. 


256 


THE  FROXTAL  SIX  US 


Fig.  252  is  a  posterior  view  of  the  frontal  sinuses,  showing  two 
incomplete  septa.  The  incompleteness  of  the  latter  is  more  than 
likely  due  to  pathological  conditions. 


Fig.  251. — Anterior  view,  showing  two  very 
large  frontal  sinuses  extending  upward  and 
well  back  over  the  orbits. 


Fig.  252. — Posterior  view,  showing  two  incom- 
plete septa. 


Fig.  253.— Two  lateral  views  of  two  specimens,  showing  large  frontal  smuses. 

Fig.  253  is  made  from  two  specimens,  showing  lateral  views  of  the 
frontal  sinuses.  The  lower  picture  is  a  sagittal  section  cut  near  the 
centre  of  the  orl)it,  showing  in  the  anterior  portion  a  lateral  view  of 


DEVELOPMENT 


257 


tlic  frontal  sinus  cli\  itlcd  inUj  li\c  pockets,  all  (-»!  which  haxe  one  com- 
mon outlet.  The  sixth  or  posterior  cell  communicates  with  the  upper 
meatus  of  the  nose.  The  Uj)per  picture  is  also  a  sagittal  section  cut  to 
the  median  line  of  the  os  planum  of  the  ethmoid  bone.  It  shows  a 
frontal  sinus  extending  backward  nearh'  to  the  optic  ner\e  which  is 
seen  in  position  in  the  optic  foramen. 

The  skull  i)ictured  in  Figs.  254,  255  and  256  has  the  largest  pneu- 
matic spaces  of  any  head  I  have  examined,  not  only  of  the  frontal 
sinus,  but  of  the  supra-orbital,  si)henoid,  and  maxillary  sinuses.  The  right 
frontal  sinus  commences  in  the  right  temporal  fossae  at  a  point  near 
the  articulation  of  the  frontal  bone  with  the  great  wing  of  the  sphenoid 


Fig.  254. — An  anterior  view  of  a  skull  with  frontal  sinuses  extending  from  within  the  great  wing  of 
the  sphenoid  hone  forward  to  the  frontal  bone  then  backward  to  the  left  sphenoid  bone. 

(see  point  marked  8,  Fig.  255).  It  extends  forward  and  across  the 
skull  to  the  opposite  side,  then  a  little  backward,  terminating  near 
the  left  great  wing  of  the  sphenoid  (see  point  marked  4,  Fig.  256). 

The  frontal  portion  of  this  great  space  is  divided  into  four  compart- 
ments, three  of  which  have  a  separate  outlet,  while  the  fourth  is  con- 
nected to  one  of  the  others  by  a  small  foramen  which  is  placed  low 
down  in  the  sinus. 

As  already  stated  the  right  frontal  sinus  commences  at  a  point 
marked  8,  in  Fig.  256,  in  the  temporal  fossae  and  extends  upward, 
forward  and  inward  almost  to  the  nasion,  measuring  55  mm.  The  right 
supra-orbital  sinus  commences  in  the  zygomatic  fossa  (see  point  marked 
9,    Fig.    255)    or   in    the   right   wing   of   the   sphenoid   bone;  it   passes 

17 


258 


THE  FRONTAL  SINUS 


upward,  forward  and  inward  over  the  orbits  (see  point  marked  7, 
Fig.  255).  Its  outlet  is  in  the  anterior  and  lower  portion  of  the  right 
frontal  sinus.  It  measures  in  length  55  mm.  There  are  also  several 
other  sinuses  or  cells  over  the  anterior  portion  of  the  orbits  with  inde- 
pendent outlets. 


Fig.  255. — Right  lateral  view  of  skull  shown  in  Figs.  254  and  256. 


Fig.  256. — Left  lateral  view  of  skull  shown  in  Figs.  254  and  255. 

The  left  frontal  sinus  commences  in  the  temporal  fossa  at  a  point 
marked  4,  in  Fig.  256.  It  then  passes  upward,  forward,  and  to  the  right, 
to  the  wall  forming  an  intermediate  frontal  sinus.  It  measures  48 
mm.  The  sinus  is  divided  into  tw^o  compartments  by  a  septum  lying 
at  an  angle  of  35  degrees  from  the  horizontal.  At  the  lower  and  median 
end  of  this  septum  there  is  a  small  foramen  w^hich  allows  the  two 
compartments  to  communicate  w4th  one  common  outlet  into  the  nasal 
cavity. 


CHAPTER    X. 

THE  ETHMOIDAL  AND  OTHER  CELLS  WHICH  HAVE 
THEIR  EIXAL  OUTLET  IX  THE  NASAL  CAXITV. 

The  ethmoidal  cells  are  situated  j^rincipalK  between  the  two 
orbits.  Fig.  257  is  an  upper  \ie\v  of  a  horizontal  section  cut  through 
the  centre  of   the  orbits  and    the    ujjper   part  of    the    nasal    cavities, 


Xasal  cavity 

Hiatus  semilunaris 
Lacrimal  due: 


Xasal  septum 


Anterior 
ethmoidal  cells 


Floor  of  orbi: 


Middle 
ethmoidal  cells 


Posterior  ethmoidal  cells 

Sphenoidal  sinuses 
Fig.  257. — Ipper  surface  of  a  horizontal  section  cut  through  the  orbits  and  upper  part  of  nasal  cavity. 

showing  clearh-  the  position  of  many  of  the  cells,  as  does  also  Fig.  258. 
Many  of  these  ethmoidal  cells  are  formed  by  the  union  of  the  orbital 
plates  of  the  frontal  bone  and  the  ethmoid  bone  and  between  the 
ethmoid  bone  and  the  maxilla;  others  are  within  the  ethmoid  alone. 
They  are  divided  into  three  groups — anterior,  middle,  and  posterior. 

The  anterior  ethmoidal  cells  are  the  smallest  of  the  three  divisions. 
They  open  by  several  small  orifices  into  the  anterior  portion  of  the 


260        ETHMOIDAL  AXD  OTHER  CELLS  IN  THE  NASAL  CAVITY 

hiatus  semilunaris.  Occasionally  a  chain  of  cells  is  found  opening  one 
into  another  and  finally  into  the  hiatus. 

The  middle  ethmoidal  cells  vary  more  in  size  than  either  the  anterior 
or  the  posterior.  The  inner  covering  or  wall  of  the  cells  is  spheroidal 
in  form  and  is  known  as  the  bulla  ethmoidalis.  It  is  situated  in  the 
upper  portion  of  the  lateral  wall  of  the  hiatus  semilunaris,  and  extends 
downward  and  inward  toward  the  unciform  process.  The  openings 
of  the  cells  are  in  the  outer  portion  of  the  bulla  ethmoidalis  and  they 
discharge  into  the  hiatus  semilunaris. 

The  posterior  ethmoidal  cells  are  usually  two  or  three  in  number. 
They  are  found  on  about  the  same  plane  as  the  anterior  and  middle 
ethmoidal  cells,  are  irregular  in  shape,  and  usually  have  their  general 
outlet  into  the  superior  meatus. 

THE    ORBITAL    PROCESSES. 

The  cells  of  the  orbital  processes  of  the  palate  bones  are  two  in 
number,  one  on  each  side.  Each  cell  is  small  and  situated  below  the 
posterior  part  of  the  floor  of  the  orbit.  It  is,  like  many  other  air  cells, 
irregular  in  shape  and  size.  It  opens  into  the  third  or  superior 
meatus.  It  occasionally  extends  backward  near  to  the  sphenoidal  sinus 
or  outward  around  the  posterior  wall  of  the  maxillary  sinus,  from  which 
it  is  separated  by  a  thin  plate  of  bone  (see  Figs.  213  and  214). 

THE    SPHENOIDAL   SINUSES. 

The  sphenoidal  sinuses  are  two,  one  on  each  side,  irregular  in  shape 
and  size,  situated  in  the  body  of  the  sphenoid  bone  (see  Figs.  257,  258 
and  280).  The  septum  between  them  is  generally  deflected  to  one  side 
or  the  other  (see  Figs.  257,  279  and  280).  Incomplete  septa  may 
also  be  found  at  the  posterior  portion  of  these  cavities,  which  divide 
them  into  several  incomplete  compartments  (see  Figs.  279  and  280.) 
Sometimes  these  sinuses  may  extend  backward  to  the  basilar  process 
of  the  occipital  bone,  or  forward  to  the  cribriform  plate  of  the  ethmoid 
bone,  or  laterally  into  the  base  of  the  great  wings  of  the  sphenoidal 
bone,  or  into  the  clinoid  process  (see  Figs.  217  and  218).     They  are 


THE  sri/i:\()fi).\r  sfxrsEs 


261 


lined  willi  mucous  membrane,  which  is  continuous  with   the  lining  of 
the  ui)iH'r  and  jK^sterior  portion  of  the  nasal  cavities. 

The  greater   jjortion   of   the  anteri(jr  surface  of   the   lj(jdy   of   the 
sphenoid  bone  is  open,  these  openings  are  covered  to  a  great  extent 


Fig.  258. — Horizontal  section  through  the  orbits,  ctlinioid  cells  and  sphenoidal  sinuses. 

by  the  sphenoid  conchas  (sphenoidal  turbinate  processes)  which  are 
two  thin  triangular-shaped  plates.  The  posterior  surface  is  concave 
and  faces  the  body  of  the  sj^henoid  bone  to  which  it  becomes  attached. 
The  anterior  surface  is  convex  and  is  associated  with  the  ethmoid  in 


262        ETHMOIDAL  AXD  OTHER  CELLS  IN  THE  NASAL  CAVITY 

front,  forming  a  portion  of  the  roof  of  the  nasal  cavity,  through  each 
of  these  plates  is  an  ostium  that  gives  passageway  from  the  sphenoidal 
sinus  to  the  highest  meatus  of  the  nose.  Pathological  conditions 
arising  through  abnormal  irregularity  of  these  conchae  are  difficult  to 
diagnose  and  treat. 

Fig.  258  is  from  a  horizontal  section  cut  through  the  centre  of  the 
orbits,  ethmoid  cells  and  sphenoidal  sinuses.  The  sphenoidal  sinuses 
are  large  with  a  slightly  curved  septum  between  them.  Cross  sec- 
tions of  the  carotid  canal  may  be  seen  posterior  to  the  sinuses. 

CELL    OF    THE    CRISTA    GALLI. 

Sometimes  a  cell  is  found  within  the  crista  galli  (see  Figs.  269, 
281,  282,  292,  293,  294,  295  and  296).  In  such  a  case  the  opening  is 
in  front  and  communicates  with  one  of  the  frontal  sinuses.  It  might 
be  termed  an  extension  of  the  frontal  sinus  into  the  crista  galli. 


CHAi'ri:R  XI. 

VARIATIONS    IN   THK   ANATOAIK  AL   STRlCTrRES 

OF   THK   PACK. 

The  variations  exhibited  in  tlie  internal  anatom>'  of  the  face  are 
so  common  that  it  is  sometimes  difficult  to  differentiate  the  normal 
from  abnormal  anatomy.     Some  of  the  most  imi)ortant  and  common 


Fig.  259. — Front  view  of  asymmetrical  skull,  showing  the  right  side  more  fully  developed  than  the 

left  side. 

variations    found    in    the    writer's    dissections    are    described    in    the 
following  pages. 

Fig.  259  is  a  front  view  of  a  skull  which  has  an  asymmetrical  arch 


264 


VARIATIOXS  IX  AX  ATOMIC  AL  STRUCTURES  OF  FACE 


of  the  mouth.     The  greater  portion  of  the  teeth  have  been  lost  in 
early  life.    The  canine  fossa  of  the  right  side  is  lacking,  the  face  being 


%T.^ 


Fig.   260.— Vertical  transverse  division  of  Fig.  259,  showing  a  larger  maxillary  sinus  on  the  left  side 

than  on  the  right. 

very  prominent  at  that  point.     The  teeth  have  not  been  in  normal 
position.     The  septum  is  deflected   toward   the  left  side.     In  a  skull 


r.lA7.l770.V.S    I.\    AXATOMICAL  STRLCTL  RJ:.S  UI-    J' ACE 


2()o 


of  this  character  tlic  inlcrnal  structures  will  usually-  be  clecicleclly 
unsyninietrical.  One  nii^ht  supjxjse  thai  a  lari;e  sinus  would  be 
found  under  the  fulness  of  the  canine  fossa,  but  in  this  jjarticular  case 
it  is  rather  small. 

Fig.  260  represents  a  vertical  transverse  section  of  the  skull  shown 
in  Fig.  259.  It  will  be  seen  that  the  right  sinus  is  smaller  than  the 
left,  the  fulness  of  the  region  in  the  infra-orbital  foramen  and  the 
canine  fossa  being  due  to  the  thickness  of  the  bone.  The  frontal  sinus 
of  this  specimen  is  large  and  extends  d(nvnwar(l  between  the  orbits 
lower  than  usual. 


«* 


Fig.  261.  Auicrior  view  of  a  vertical  trans- 
verse section  of  skull  through  the  centre  of  the 
orbits,  nasal  cavity,  and  maxillary  sinus,  the 
lower  inner  corners  of  the  maxillary  sinuses 
passing  partly  under  the  nasal  cavity. 


Fig.  202. — Posterior  \  iew  of  a  vertical  trans- 
\erse  section  of  skull  in  region  of  second  pre- 
molar, showing  lack  of  symmetry  in  nasal  cavity 
and  maxillary  sinuses,  with  the  septum  and 
"spur"  passing  over  the  inferior  concha. 


Fig.  261  exhibits  a  condition  occasionally  met  with,  the  floor  of 
the  sinus  dipping  downward  and  passing  partly  under  the  floor  of 
the  nose.  The  same  condition  will  be  found  in  Figs.  284  and  297. 
Resorption  has  taken  place  between  the  plates  forming  the  floor  of  the 
nose  and  the  roof  of  the  mouth.  Sinuses  like  these  could  be  drained 
directly  by  an  opening  through  the  palatal  surface  of  the  mouth.  In 
skulls  of  this  character  the  vault  of  the  mouth  is  high. 

Fig.  262  exhibits  an  entire  lack  of  symmetry  between  the  nasal 
cavity  and  the  sinuses  of  the  right  and  left  sides,  the  inferior  meatus  of 


266 


VARIATIOXS  IX  AX  ATOMIC  AL  STRUCTURES  OF  FACE 


one  side  being  closed  anteriorly  by  the  deflected  nasal  septum  and  the 
"spur"  upon  it.  In  such  cases  as  this,  inspissated  mucus  often  collects 
and  the  outlet  of  the  nasolacrimal  duct  may  be  interfered  with. 

Figs.  263,  264  and  265  are  from  the  same  subject  as  Fig.  262.    An 
instrument  passed  through  the  axis  of  the  alveolar  process,  shown  in 


Fig.  263. — Anterior  view  of  a  vertical  trans- 
verse section  of  the  skull  shown  in  Fig.  262, 
showing  an  asymmetrical  condition  of  the  two 
sides. 


Fig.  265. — Anterior  view  of  vertical  trans- 
verse section  cut  from  the  posterior  part  of  the 
nasal  cavity  and  maxillary  sinus.  It  is  from 
the  same  skull  as  Figs.  262,  263  and  264. 


Fig.  264. — Posterior  view  of  section  shown 
in  Fisr.  263. 


Fig.  266. — Anterior  view  of  a  vertical  trans- 
verse section,  showing  lack  of  uniformity  in  the 
two  maxillary  sinuses. 


the  right  side  of  Fig.  264  or  the  left  side  of  Fig.  263  or  Fig.  265,  would 
perforate  the  nasal  cavity,  instead  of  the  floor  of  the  maxillary  sinus. 

Fig.  266,  which  is  taken  from  a  different  skull,  shows  an  almost 
straight  septum,  with  bilateral  symmetry  as  regards  the  nasal  cavity; 


VARf.iriOXS   l.\   AXATOMfCAL  STRl'CTLRES  OF  FACE 


20^ 


the  ma\illar\'  sinuses  \ar\',  howewr,  thnnighcnit  the  depth  of  the 
skull.  On  the  rii;ht  side  the  sinus  wcnild  not  he  reached  In-  drilling 
through  the  alveolar  process,  while  on  the  left  side  the  sinus  is  just 
above  the  i)rocess,  and  the  floor  is  below  the  level  of  the  floor  of  the 
nasal  cavity. 

Fig.  267  is  from  a  vertical  transverse  section  in  the  region  of  the 
first  premolar.  The  septum  is  almost  straight,  but  there  is  a  great 
variation  in  the  maxillar\-  sinuses.  The  lateral  wall  of  the  nasal  cavit>- 
of  the  right  side  is  also  the  outer  plate  of  the  maxilla,  the  floor  of 
the  sinus  being  on  a  much  higher  ])lane.     In  the  floor  of  the  left  nasal 


Fig.  267. — Anterior  view  of  a  vertical  transverse  section,  near  the  first  premolar,  showing  variation 
in  the  niaxillar\-  sinuses  and  the  nasal  cavities. 

cavity  is  an  elevation  which  covers  a  tooth  root,  probably  that  of  a 
supernumerary  tooth.  In  Figs.  263  and  267  the  nasal  walls  of  the 
right  inferior  meatus  pass  outward  under  the  maxillar}'  sinus  to  the 
facial  portion  of  the  maxillary  bone.  In  Figs.  270  and  283,  the 
same  condition  will  be  observed  on  both  sides.  In  the  event  of 
attempting  to  drill  into  the  maxillar\-  sinus  from  the  canine  fossa 
in  such  cases  as  are  represented  in  these  figures,  as  is  sometimes 
advised,  the  opening  would  be  made  into  the  nasal  cavity  instead  of 
into  the  sinus. 

Fig.  268  is  a  vertical  transverse  section  made  in  the  region  of  the 
second  molar,  the  nasal  cavities  are  large  with  a  straight  sci')tum.  the 


268 


VARIATIOXS  IX  AX  ATOMIC  AL  STRUCTURES  OF  FACE 


Fig.  268. — Posterior  view  of  a  vertical  section  made  in  the  region  of  the  molar  teeth,  showing  small 
sinuses  and  large  nasal  cavity  and  narrow  dental  arch. 


Fig.  269. — Two  vertical  transverse  sections.  The  surfaces  shown  arc  divided  from  each  other. 
Variations  are  shown  in  the  maxillary  sinuses  and  nasal  cavity.  A  cell  is  also  shown  within  the  crista 
gain,  which  opens  into  the  frontal  sinus. 


WlRIAIfOXS  /.V  ANATOMICAL  STKiCTL'RliS  Oh'  FACK  2(i9 

dental  arch  is  narrow  and  the  nui.\inar>-  sinuses  small,  the>-  do  n(;t 
extend  downward  in  the  direction  of  the  teeth  and  alveolar  i)rocess. 

Fig.  269  shows  two  sections  from  the  same  skull  as  Fig.  268,  cut 
more  anteriorly,  in  the  region  of  the  premolars.  The  parts  are  almost 
s>'mmetrical.  The  crista  galli  has  been  cut  trans\ersely,  showing 
within  its  walls  a  cell  of  considerable  size,  opening  into  the  frontal  sinus. 

Fig.  270  is  made  from  the  skull  (jf  an  aged  ])erson,  in  which  the 
bones  have  become  much  resorl^ed.  It  is  comparatively  s>m metrical, 
with  the  floor  of  the  sinus  much  higher  than  usual,  and  the  nasal  ca\it\- 
extending  outward  to  the  external  portion  of  the  maxillary  bone. 


Fig.  270. — Anterior  view  of  a  vertical  transverse  section  from  the  skull  of  an  aged  person,  showing 
large  nasal  cavities  with  small  maxillary  sinuses. 

Occasionally  in  surgical  practice  abscesses  are  found  opening  on  the 
face  in  the  region  of  the  zygomatic  bone.  These  are  usually  looked  upon 
as  of  superficial  origin,  but  sometimes  when  carefully  examined  they 
are  found  to  be  associated  with  the  maxillary  sinus.  Fig.  271  will 
partly  explain  why,  in  some  cases,  abscesses  of  the  maxillary  sinus 
open  at  this  point.  The  section  is  made  at  the  region  of  the  maxillo- 
zygomatic  articulation.  The  maxillary  sinus  passes  far  into  the  zygo- 
matic bone,  extending  backward  into  the  temporal  process. 

Fig.  272  is  from  a  skull  in  which  the  nasal  cavity  extends  outward 
over  the  alveolar  process  until  it  reaches  the  outer  wall  of  the  maxilla. 
The  points  of  the  palatal  roots  of  the  first  and  second  molars  appear 
in  the  floor  of  the  nasal  cavity.  The  floor  of  the  maxillary  sinus  is 
well  up  on  the  side  of  the  bone. 


270 


VARIATIOXS  IX  ANATOMICAL  STRUCTURES  OF  FACE 


Fig.  2"/^,. — A  sagittal  section  of  a  greyhound's  skull,  showing  the 
nasal  cavity  extending  to  the  outer  wall  of  the  maxilla,  no  true  maxil- 
lar\-  sinus  is  found,  though  the  inferior  concha  helps  to  partly  shut  off 
a  space  which  might  be  named  the  conchomaxillary  sinus. 


Fig.  271. — Section  through 
the  maxillozygomatic  articula- 
tion, showing  that  occasionally 
the  maxillary  sinus  passes  into 
the  zygoma. 


Fig.  272. — Interior  view  of  the  external  wall  of  the  nasal 
cavity,  showing  portions  of  the  palatal  roots  of  the  first  and 
second  molar  teeth  in  the  floor  of  the  nose. 


Fig.  273. — Sagittal  section  of  a  greyhound's  skull. 

Fig.  274. — A  sagittal  section  of  a  badger,  showing  conditions  similar 
to  that  of  the  greyhound,  Fig.  273.  The  root  of  a  tooth  is  seen  in  the 
floor  of  the  nasal  cavity  similar  to  the  roots  shown  in  the  human  nasal 
cavity,  Fig.  272. 

Fig.  275  is  a  picture  from  the  external  or  facial  surface  of  Fig.  272, 
which    illustrates   that   the   resorption   of    the   alveolar   process   from 


VARIAT/O.XS  I.\  A.XATOMICAL  STRUCTURES  OF  FACE 


271 


over  the  buccal  roots  o*"  the  teeth  may  progress  while  that  portion  of 
the  bone  alon.u  the  free  mariiin  of  the  process  is  left  intact. 

Figs.  276  and  277  show  a  \  ertical  transverse  section  of  the  upper 
jaw.  In  Fig.  277  the  roof  of  the  niaxillar\-  sinus  is  almost  horizontal, 
which   is  a  \er\    unusual   condition.      The   illustrati(jns  show  what   is 


Fig.  274. — Sagittal  section  of  a  badger's  skull. 


Fig.  275. — E.xternal  view  of  facial  surface  of  Fig.  272,  showing  the  resorption  of  the  outer  part  of 
the  alveolar  process,  leaving  a  line  of  bone  near  the  free  margin  of  the  process. 

apparently  a  division  of  the  sinus  into  two,  the  smaller  or  outer  division 
forming  an  infra-orbital  sinus.  This  condition  is  caused  by  a  bony  septum 
passing  down  from  the  centre  of  the  floor  of  the  orbit,  cutting  off  a  por- 
tion ot  the  sinus,  and  forming  an  extra  chamber,  which  of  course  is  con- 
tinuous with  the  true  sinus.     In  the  centre  of  the  septum-like  wall  is 


272  VARIATIOXS  IX  ANATOMICAL  STRUCTURES  OF  FACE 


Infra-orbital  nerve — !^ 


Muscles  of  face    — ;'   -/"y^-AP 


Middle  ethmoidal  cells 


Middle  concha 
Unciform  process 


—Inferior  concha 
Inferior  meatus 


Fig.  276. 


Middle 
ethmoidal  cells 


Hiatus  semilunaris 
Unciform  process 


Ma.xillary  sinus — -» 
Inferior  concha—^-'/ 
Inferior  meatu 


Infra-orbital  nerve 


-  Muscles  of  face 


Fig.  277. — Vertical  transverse  division  of  the  upper  jaw. 


VAR/AT/OXS  IN  ANATOMICAL  STRiCTURES  OF  FACE  273 

a  tube  (jr  canal  coiucxin^  the  inlra-(jrl>ital  nerves  and  vessels.  Above 
this,  and  at  the  junction  of  the  septum  with  the  floor  of  the  or])it  is 
an  adjunct  infra-orbital  canal  and  ner\e.  At  the  ui)j)er  inner  corner 
of  Fig.  277  is  the  normal  opening  of  the  maxillary  sinus,  the  ostium 
maxillare.  communicating  with  the  hiatus  semilunaris.  This  section 
beautifulK'  illustrates  how  the  hiatus  semilunaris  is  bounded  on  the 
inner  side  l)y  the  unciform  process,  on  the  outer  side  by  the  wall  of 
the  sinus,  and  above  1)\  the  bulla  ethmoidalis,  containing  the  middle 
ethmoidal  cells.  Should  the  bulla  become  enlarged,  or  the  mucous 
membrane  of  this  region  be  swollen,  the  hiatus  would  be  closed   and 


Fig.  278. — Posterior  view  of  vertical  section  Ihruugh  ihe  orbits,  maxillary  sinuses,  posterior  ethmoidal 

cells,  and  the  third  molar  teeth. 

fluids  could  not  pass  directh'  into  the  middle  meatus  but  would  be 
thrown  into  the  maxillar^,^  sinus. 

Fig.  278  illustrates  a  vertical  transverse  section  of  the  face.  It 
gives  a  good  sectional  view  of  the  posterior  ethmoidal  cells.  The  white 
line  is  on  a  level  with  the  floor  of  the  orbit  in  the  anterior  portion  of 
the  section.  It  will  be  noticed,  as  is  often  the  case,  that  the  roof  of 
the  maxillary  sinus  runs  up  as  it  passes  backward  until  it  is  far  above 
the  level  of  the  floor  of  the  orbit  at  its  anterior  margin. 

Figs.  279  and  280  show  two  sections  made  by  a  horizontal  trans- 
verse section  a  little  below  the  roof  of  the  sinus.  In  this  case  the 
commencement  of  the  ostium  maxillare  is  within  the  roof.  It  passes 
backward  and   inward   to  the  hiatus  semilunaris.     A  j^robe  {ilaced  in 

18 


274 


VARIATIOXS  IX  AX  ATOMIC  AL  STRUCTURES  OF  FACE 


Ostium 

maxillare 
opening  in 
roof 


.   ■     -, —  Sphenoidal 
'f>i.'  sinus 


Fig.  279 


Sphenoidal  sinus 


Middle  concha 


Middle 

meatus 

Maxillary 

sinus 

Inferior 

concha 

Zygomatic 

bone 

Nasolacrimal 

duct 


Nasal  septum 


Fig.  280 
Figs.  279  and  280. — Two  illustrations.    Fig.  279  shows  the  roof  of  the  maxillary  sinus  and  upper  por- 
tion of  the  nasal  cavity;  Fig.  280  shows  the  maxillary  sinus  and  nasal  cavity. 


VARJATIOAS   l.\   AXATDMJCAL  STKUCTLRES  Ul-    FACE  27.") 

the  left  ostium  maxillarc  indicates  its  position.  Immediately  to  the 
left  of  the  i)robe  is  a  section  of  the  nasolacrimal  duct.  On  the  opposite 
side,  the  lower  wall  of  the  rii^ht  ostium  has  been  removed. 

That  the  ij,reat  \arialioiis  found  in  the  nasal  ca\ities  and  maxil- 
lary sinuses  may  be  fully  appreciated,  skulls  of  wideh  different  types 
have  been  selected  and  phototirai:)hed  together. 

Figs.  281  and  2H2  give  a  posterior  view  of  two  sections  made  from 
different  skulls.  They  show  great  variations  in  the  depth  of  the  face, 
and  the  size,  shape,  and  position  of  the  maxillary  sinus.  In  Fig.  281 
the  sinuses  are  much  smaller  than  in  the  shorter-faced  picture,  F'ig. 
282.  In  Fig.  281  the  septum  has  a  spur  extending  outward  until  it 
comes  in  contact  w^ith  the  inferior  concha,  the  frontal  sinuses  pass 
well  down  below  the  level  of  the  centre  of  the  orbits.  In  both  illus- 
trations there  are  distinct  cells  in  the  crista  galli,  which  open  anteriorly 
into  the  frontal  sinuses. 

Figs.  283  and  284  were  made  in  the  same  manner  as  Figs.  281  and 
2S2,  and  show  two  sections  cut  in  about  the  same  position  from  two 
different  skulls.  There  is  again  a  great  difference  in  the  depth  of  the 
faces.  The  maxillary  sinuses  in  Fig.  283  are  small  and  placed  high 
up,  allowing  the  lower  portion  of  the  nasal  cavity  to  extend  outward 
over  the  alveolar  process.  In  Fig.  284  the  maxillary  sinuses  are  large, 
their  floors  extending  down  below  the  floor  of  the  nasal  cavity,  and 
passing  inw^ard  over  the  roof  of  the  mouth,  so  that  only  a  small  space 
is  left  between  the  sinuses.  The  enlarged  sinuses  allow  but  little  room 
for  the  nasal  cavities. 

Figs.  285  and  286,  also  made  from  two  different  skulls,  show 
variations  in  the  depth  of  the  nasal  cavities.  A  good  illustration  of 
the  fourth  meatus  and  a  part  of  a  fifth  is  shown  in  Fig.  285. 

Figs.  281,  282,  283,  284,  285  and  286  serve  to  show  several  varia- 
tions in  the  sinuses  and  nasal  cavities.  Similar  comparisons  between 
the  sphenoidal  and  frontal  sinuses,  and  the  ethmoidal  and  other  cells, 
would  show  as  marked  differences.  Bilateral  variations  almost  equally 
extensive  are  found  in  the  individual  skull,  except  as  to  the  depth  of 
the  face.  The  diagnosis  and  surgery  of  such  cases  must  follow  in 
accordance  with  the  variations  existing  in  the  anatomical  structures. 


276 


VARIATIOXS  IX  ANATOMICAL  STRUCTURES  OF  FACE 


In  Fig.  287  is  shown  an  anteroposterior  section  illustrating  the 
close  relation  between  the  frontal  and  maxillary  sinuses.  It  also  shows 
that  in  this  instance  fluids  could  pass  from  the  frontal  sinus  and  eth- 


Cell  within 
crista  galli 


Fig.  281 


Fi(i.  282 
Figs.  281  and  282. — Posterior  views  of  two  vertical   transverse  sections  made  from  different 
skulls  in  about  the  same  anatomical  region,  showing  great  variations  as  to  the  depth  of  face,  and 
size  and  shape  of  the  maxillary  sinuses  and  nasal  cavities. 


VARlATfO.XS   l.\   AXATOMICAL  STRL'CTLRKS  OF  I'ACK  277 

moidal  cells  into  the  maxillan-  sinus.    Of  the  two  probes  passed  throui^h 
the  ostium  niaxillare.  one  uoes  directK'  throui^h  the  jxjsterior  i)ortion 


Fig.  283  Fig.  284 

Figs.  2SS  and  ISA. — Posterior  views  of  two  vertical  transverse  sections  made  from  different 
skulls  in  about  the  same  anatomical  region,  showing  great  variations  as  to  the  depth  of  face,  and 
size  and  shape  of  nasal  cavities  and  maxillary  sinuses. 


Fig.  285  Fig.  286 

Figs.  285  and  286. — Two  illustrations  from  different  subjects,  showing  great  variations  as  to  depth 
and  size  in  the  external  wall  of  the  nasal  cavities.     Fig.  285  shows  four  meatuses. 


278 


VARIATIOXS  IX  ANATOMICAL  STRUCTURES  OF  FACE 


of  the  hiatus  semilunaris  into  the  middle  meatus,  while  the  other 
(the  vertical  one)  passes  into  the  hiatus  semilunaris,  then  upward 
and  a  little  forward  into  the  frontal  sinus. 

Fig.  288  is  an  anterior  view  of  a  transverse  vertical  section,  showing 
the  lower  portion  of  the  frontal  sinuses  on  both  sides,  with  a  probe 


Fig.  287. — Antero-posterior  section  showing  inner  wall  of  the  orbit,  and  the  maxillary  sinus  with 
two  probes  through  the  ostium  maxillare.  The  conical  elevation  in  the  floor  of  the  sinus  is  where  a 
root  of  a  tooth  has  been  left,  retarding  resorption  in  this  part  of  the  floor,  in  the  remainder  of  which 
the  process  has  been  active. 


passed  from  the  right  sinus  downward  and  slightly  outward  along  the 
hiatus  semilunaris,  and  then  through  the  ostium  maxillare  into  the 
maxillary  sinus.  It  will  be  noticed  that  there  is  quite  a  difference  in 
the  anatomical  characteristics  of  the  anterior  ethmoidal  cells. 


VARIAT/OXS  IX  AN  ATOM  KM.  STRUCTURES  OF  FACE 


279 


Fig.  289  is  a  posterior  view  of  the  same  section  as  Fig.  2S8.  The 
course  of  the  i)rol)c  can  he  traced  as  it  passes  downward  along  the  hiatus 
semikniaris,  through  tlie  ostium  maxillare,  and  into  the  sinus  without 
obstruction.  There  is  a  hick  of  bilateral  symmetry  in  the  unciform 
process  and  bulla  ethmoidalis.  As  this  is  a  section  of  a  negro  skull,  the 
great  thickness  of  the  floor  of  the  maxillary  sinus  is  accounted  for. 

Fig.  290  gives  another  view  of  the  hiatus  semilunaris  leading  down- 
ward and  l)ackward  from  the  frontal  sinus  into  the  middle  meatus,  a 


V\o.  288. — Anterior  view  of  a  vertical  trans- 
verse section  of  a  negro  skull  between  the  second 
premolar  and  the  first  molar  tooth,  showing  probe 
passing  down  into  the  maxillary  sinus,  through 
the  frontal  sinus,  the  hiatus  semilunaris,  and 
ostium  maxillare. 


r^ 


Fig.  289. — Posterior  view  of  section  shown 
in  Fig.  288. 


portion  of  the  walls  (bulla  ethmoidalis)  covering  the  middle  ethmoidal 
cells  having  been  cut  away. 

Fig.  291  shows  two  hiatuses,  or  infundibula,  leading  directly  into 
maxillary  sinus.  Through  the  posterior  hiatus  a  probe  has  been  passed, 
the  outer  wall  of  the  anterior  one  having  been  cut  awa^^  in  order  that 
a  better  view  could  be  obtained. 

Figs.  292  and  293  illustrate  a  vertical  transverse  section,  show- 
ing more  direct  communication  between  the  frontal  and  maxillary 
sinuses  than  Figs.  288  and  289.  They  give  posterior  and  ante- 
rior   views    of    the    same    section.    Fig.    292     having     that    portion 


2S0 


VARIATIOXS  IX  AX  ATOMIC  AL  STRUCTURES  OF  FACE 


of  the  face  removed  which  extends  back  to  the  premolar  teeth 
below,  and  exposes  the  frontal  sinuses  above.  The  septum  of  the 
nose  is  deflected  and  a  "spur"  reaches  over  to  the  right  concha.    The 


Fig.  290. — Interior  view  of  the  lateral  wall 
of  the  nasal  cavity  with  part  of  the  bone  cut 
away  to  show  the  hiatus  semilunaris  and  the 
middle  ethmoidal  cells. 


Fig.  291. — Section  showing  two  hiatuses,  both 
leading  directly  into  the  maxillary  sinus.  The 
posterior  hiatus  has  a  probe  passing  through  it, 
the  anterior  one  has  the  external  wall  cut  away 
in  order  that  a  better  view  may  be  obtained. 


Fig.  292 


Fig.  293 


Figs.  292  and  293. — Anterior  and  posterior  views  of  a  vertical  transverse  section. 


VARIATJOAS  J.\    A.XAJOMICAL  STRLCnRKS  OF  I'ACK 


2S1 


frontal  sinuses  extend  down  l)el()\v  the  middle  of  the  orbit.  Between 
them  there  is  an  interfrontal  cell  extending  backward  into  the  crista  ^^alli 
as  is  shown  in  Fig.  293.  A  wire  passed  downward  from  the  right  frontal 
sinus  is  again  seen  in  the  maxillary  sinus.  Fig.  293  shows  the  section 
cut  posteriorh'  to  the  first  molar  teeth.  The  frontal  sinuses  extend 
in  an  outward  direction  o\er  the  orbits.  The  wire  shown  in  F'ig.  292 
is  seen  passing  downward  from  the  right  frontal  sinus  through  the 
infundibulum  and  hiatus  semilunaris  and  entering  the  maxillary  sinus 
through  the  ostium  maxillare. 


%-  ^ 


Fig.  294.— Anterior  view  of  vertical  transverse  section  in  the  region  of  the  first  molar  teeth, 
showing  anterior  ethmoidal  cells,  and  a  cell  in  the  crista  galli.  The  frontal  sinus  extends  downward, 
becoming  common  with  the  ethmoidal  cells  and  maxillary  sinus. 

Fig.  294  shows  an  anterior  view  of  a  vertical  trans^•erse  section  in 
the  region  of  the  premolar  teeth.  Between  the  orbits  are  seen  the 
anterior  ethmoidal  cells,  and  also  a  sinus  in  the  crista  galli.  In  this 
case  both  sinuses  extend  upward  and  become  common  with  the  ethmoidal 
cells  and  frontal  sinuses. 

Fig.  295  gives  a  posterior  view  of  a  vertical  transverse  section  cut 
in  the  region  of  the  first  molar  teeth  and  through  the  crista  galli.  The 
septum  is  deflected  toward  the  left  side:  the  right  maxillary  sinus 
extends  upward  and  inward,  terminating  in  a  large  opening  into  the 


282 


VARIATIOXS  I\  AXATOMICAL  STRUCTURES  OF  FACE 


hiatus  semilunaris  without  a  true  hne  of  demarcation.  The  left  maxil- 
lary sinus  extends  forward  into  the  infra-orbital  ridge,  forming  an 
infra-orbital  sinus  somewhat  similar  to  those  shown  in  Figs.  223,  224, 
229,  230,  276  and  277.  The  numerous  pockets  in  the  anterior  portion 
of  the  maxillary  sinus  would  render  it  difficult  to  treat  should  it 
become  diseased. 

Fig.  296  shows  a  posterior  view  of  a  vertical  transverse  section  from 
the  skull  of  an  aged  person.    The  floor  of  the  maxillary  sinus,  the  nasal 


-ae****'- 


Infra-orbital  sinus 
Infra-orbital  canal 


Hiatus  semilunaris 


Fig.  295. — Posterior  view  of  a  vertical  transverse  section  through  the  first  molar  teeth.  The 
right  hiatus  semilunaris  in  this  subject  communicates  with  the  maxillary  sinus  without  a  true  ostium 
maxillare. 


and  the  lower  border  of  the  alveolar  process  are  almost  on  a  horizontal 
line.  The  left  maxillary  sinus  extends  upward  until  it  passes  into 
the  frontal  sinus,  without  any  line  of  demarcation  between  sinuses 
or  cells.  In  the  crista  galli  is  seen  a  small  sinus  or  cell  w^hich  extends 
forward  into  the  frontal  sinus.  This  last  formation  is  also  shown  in 
Figs.  269,  2S1,  282,  292,  293  and  294. 

Fig.  297  shows  a  posterior  view  of  a  vertical  transverse  section 
cut  behind  the  first  molar  teeth.  The  maxillary  sinuses  are  almost 
cuboidal  in  shape  and  extend  down  below  the  floor  of  the  nasal  cavities 


VAIUATIUSS  IN  ANATOMICAL  STRUCTLRES  OF  FACE 


283 


Fig.  296. — Posterior  view  of  a  vertical  transverse  section  in  the  region  of  the  ostium  maxillare. 
From  the  skull  of  an  aged  person.  The  floor  of  the  nasal  cavity,  the  alveolar  process,  and  the  floor 
of  the  sinus  are  nearly  on  the  same  level.  The  left  maxillary  sinus  extends  upward  through  the  region 
of  the  anterior  ethmoidal  cell  into  the  frontal  sinus  without  a  line  of  demarcation  between  them. 


Fig.  297. — Posterior  view  of  a  vertical  transverse  section  near  the  first  molar  teeth,  showing 
maxillary  sinuses  which  are  nearly  cuboidal  in  shape  and  which  extend  downward  below  the  floor 
of  the  nasal  cavity.  The  nasal  cavity  is  narrow  and  the  walls  dividing  it  from  the  sinuses  are  concavo- 
convex  in  their  vertical  direction. 


284 


VARLiriOXS  IX  AX  ATOMIC  AL  STRUCTURES  OF  FACE 


inward  and  toward  the  medial  line,  outward  into  the  zygomatic  bones, 
and  upward  into  the  ethmoidal  cells.  The  inner  walls  are  not  straight, 
as  in  Figs.  196  and  197.  Starting  at  the  floor  of  the  sinus,  almost 
o^•er  the  centre  of  the  dome  of  the  mouth,  the  inner  wall,  as  it  extends 
upward,  curves  outwardly,  then  inwardly  to  the  point  at  which  the 
inferior  concha  projects  into  the  nasal  cavity.  This  formation  leaves 
a  very  narrow  or  contracted  nasal  cavity,  a  deformity  also  shown  in 
Fig.  284. 


Fig.  298. — Posterior  view  of  a  vertical  transverse  section  in  the  region  of  the  second  premolar, 
showing  wires  passing  from  the  frontal  sinuses  into  the  maxillary  sinuses. 

Fig.  298  is  a  posterior  view  of  a  section  made  back  of  the  premolar 
teeth.  On  either  side  a  wire  has  been  passed  from  the  two  frontal 
sinuses  down  through  the  ostium  frontalis  into  the  hiatus  semilunaris 
and  thence  into  the  maxillary  sinus;  the  wire  on  the  left  side  can  be 
seen  at  various  points  as  it  passes  downward.  This  condition  indicates 
direct  communication  between  the  frontal  and  maxillary  sinuses. 
There  are  also  two  large  cells  between  the  plates  of  the  middle  concha. 
In  the  upper  median  corner  of  the  maxillary  sinus,  especially  in  the  left 
one,  is  a  septum  forming  an  infra-orl)ital  sinus. 


CHAPTER  XII. 

THE   RELATION    BETWEEN   THE    MOITH,    TONGUE, 
PHARYNX,   AND   NASAL   CHAMBER. 

Frozen  Sections. — The  sections  of  the  head  which  ha\'e  hitherto 
been  described  were  cut  from  partly  dried  specimens  which  answer 
the  purpose  very  well,  especially  in  and  about  the  nose  and  its  asso- 
ciated sinuses  and  cells,  but  they  have  one  serious  fault — the  soft  tissues 
ha\'e  so  shrunken  that  they  are  far  from  showing  what  they  were  in 
a  fresh  condition.  Many  of  the  modern  applied  anatomists  have 
adopted  the  following  plan  for  the  study  of  the  relative  values  of  these 
parts. 

The  bodies  secured  for  this  work  should  be  those  that  have  not 
lost  their  true  anatomical  form  through  disease.  They  should  be  pre- 
pared as  soon  as  possible  after  death,  first  by  injecting  a  solution  of 
formalin  to  harden  the  soft  tissues,  followed  by  injection  of  a  magma 
of  colored  plaster  of  Paris,  after  which  the  body  should  be  covered 
with  a  coating  of  vaselin  and  wrapped  in  cloths  to  prevent  evaporation, 
and  placed  in  a  refrigerator  at  a  temperature  of  about  15°  F.  When 
thoroughly  frozen  it  is  ready  for  sectionizing.  The  saw  for  making 
the  sections  should  have  a  thin,  broad  blade,  with  fine,  chisel-shaped 
teeth;  in  this  way  the  finest  bone  can  be  cut  without  fracture,  and 
even  the  soft  tissue  of  the  brain  without  displacement. 

The  following  illustrations  are  made  from  frozen  sections: 

Fig.  299  is  an  illustration  made  from  a  section  cut  horizontally, 
just  above  the  mylohyoid  muscle  looking  upward  to  the  base  of  the 
tongue.  The  various  structures  shown  are  indicated  on  the  margin. 
It  will  be  noticed  that  the  tongue  rests  very  close  to  the  inner  surface 
of  the  mandible  and  the  pterygoideus  internus  muscle,  the  cross  section 
of  the  pharynx  is  shown  with  the  point  of  the  uvula  in  view.  Should 
the  mandible  be  compressed  and  a  narrow  dental  arch  exist,  the  tongue 


2SG 


RELATION  BETWEEN  MOUTH,  TONGUE  AND  PHARYNX 


would  be  forced  backward  into  the  pharyngeal  space,  interfering  with 
nasal  respiration  and  other  functions  of  the  nasal  cavity. 


Lower  lip 


/ 


Muscles  and  tissues  of  lower  lip 
/     The  mandible  cut  a  little  above  the 
/  J  mylohyoid  ridge 

/   ^-     /      /Sublingual  glands 

/Raphe  of  the  tongue 


Facial  artery 
Facial  vein 


Facial  vein 
—  Facial  artery 


'■*",^  -Alasseter  muscle 


The  ramus 


|fc — 1    Pterygoideus  internus 
-Point  of  uvula 

[muscle 
">   \Y^      Sternocleido  mastoid 
r  Internal  carotid 
.  'M^    Pneumogastric  nerve 
Internal  juglar 

-— Splenius  capitis 
Vertebral  artery 


Spinal  cord 


Spinous  process  of  the 
second  cervical 
vertebra 


1"1G.  299 


RELATION  BETWEEN  MOUTH,   TONGUE  AND  PHARYNX 


287 


Fig.  300  is  nuide  from  a  horizontal  section  at  the  junction  (jt  the 
upper  lip  and  nose,  showing  a  longitudinal  section  of  the  septum  (jf 


Nose 


Nostril. 


Maxilla. 

Septum  of  nose. 
Xasal  cavity 
liilurior  cuncha. 

Maxillary  sinus. 

Upper  portion  of  inferior  meatus. 

Zygomatic  process. 


)f  coronoid  process, 
sseter  muscle, 
ppcr  head  of  the  pteryguideus  cxtenius. 

iiwer  half  of  the  pterygoideus  exlernus. 
terygoid  process. 

Head  of  condyloid  process. 

Longus  capitis. 
Rectus  capitis  anterior. 

Upper  portion  parotid   gland. 
Internal  carotid  artery. 
Internal  jugular  vein. 

Jugular  process  of  occipital  bone. 
-Mastoid  cells. 

Spinal  cord. 

Under  portion  of  cerebellum. 
Uone   surrounding    foramen   magnum. 


Fig.  300 


the  nose,  the  lower  borders  of  the  inferior  concha,  and  the  ma.\illar>- 
sinus.     Within   the  outer  wall   of   the   nasal   cavity   the   longitudinal 


288  RELATIOX  BETWEEX  MOUTH,   TOXGUE  AXD  PHARYNX 

section  of  the  auditory  tube  may  be  seen,  and  a  little  posterior,  the 
phar^'ngeal  recess. 

Fig.  301  is  from  a  sagittal  section  of  a  frozen  skull,  showing  the 
various  structures  of  the  brain.  It  also  gives  a  true  idea  of  the  lateral 
portion  of  the  nasal  cavity,  the  hard  and  soft  palates,  the  pharynx, 
the  mouth,  the  tongue  and  the  epiglottis,  and  their  relations  to  each 
other.  The  first  incisor  teeth  are  in  good  occlusion.  The  mouth  is 
nearh'  filled  by  the  tongue,  leaving  but  little  space  under  the  arch  of 
the  palate.  The  tongue  also  extends  well  back  into  the  oropharynx, 
coming  in  contact  with  the  soft  palate,  which  is  carried  backward 
against  the  postphary^ngeal  wall.  The  epiglottis  at  the  base  of  the 
tongue  rests  slightly  against  the  back  of  the  pharynx,  leaving  but 
little  space  for  respiration  which,  however,  is  sufficient  when  the 
individual  is  at  rest.  But  during  exertion,  when  more  breathing  space 
is  required,  the  mouth  is  opened  and  the  space  in. the  pharyngeal  region 
is  increased.  In  this  section  the  floor  of  the  nasal  cavity  extends  from 
the  anterior  nares  backward  and  slightly  downward  almost  to  the 
postpharyngeal  wall  without  a  line  of  demarcation. 

The  general  shape  of  the  roof  of  the  mouth  at  the  median  line  is 
well  displayed,  and  may  be  described  as  extending  from  the  anterior 
teeth  backward  and  slightly  downward  in  a  concave  line  nearly  to  the 
postpharyngeal  wall. 

In  the  normal  living  subject  when  the  mouth  is  closed,  the  soft 
palate,  the  posterior  border  of  the  tongue,  and  the  epiglottis  are  all  in 
close  proximity  to  the  postpharyngeal  wall.  The  soft  palate,  on  its 
nasal  surface  is  higher  along  the  center  line  than  at  the  edges,  a  shape 
which  causes  the  fluids  from  the  nose  and  its  accessory  sinuses  and 
cells  to  be  directed  toward  the  outer  wall  of  the  pharynx  and  on  to  the 
esophagus.  The  dorsum  of  the  tongue  also  acts  in  a  similar  manner 
for  the  oral  cavity.  The  epiglottis  is  so  shaped  as  to  throw  the  fluids 
to  the  side  of  the  pharynx  past  the  opening  of  the  pharynx.  It  does 
not,  as  described  by  some,  shut  down  like  a  trap-door  over  the  glottis 
to  prevent  fluids  from  passing  into  it. 

Fig.  302  is  from  a  vertical  transverse  section  of  a  negro  head,  cut 
in   the  region  of  the   molar  teeth.     The  section  exposes  the  frontal 


RKLATIO.X   BETWKES   MOLTll,   TOMiUK  AM)  I'lIAKVXX  291 

the  sinus  directh'  downward  through  the  infun(lil)iiluni  (ostium  fron- 
talus),  the  hiatus  scMiiihuiaris,  and  the  ostium  maxillare  into  the  maxil- 
lary sinus.  Below,  and  a  little  outward  fnjm  the  frcjntal  sinuses  are 
the  transverse  sections  of  the  orbits  with  the  tissues  of  the  eye  in 
position,  in  which  may  be  seen  cross-sections  of  some  of  the  recti 
muscles.  The  dark  inner  membrane  is  the  choroid.  Between  the  orbits 
are  the  anterior  ethmoidal  cells,  the  unciform  ])rocesses,  the  hiatus 
semilunaris,  the  middle  concha,  and  the  sei)tuni  of  the  nose,  which 
passes  downward  to  the  floor  of  the  ncjse  over  the  intermaxillary  suture. 
There  is  a  slight  spur  on  the  right  side  of  the  sei)tum.  In  the  lower 
portion  of  the  nasal  cavity  are  cross-sections  of  the  inferior  concha. 
Below  the  orbits  are  two  almost  typical  maxillary  sinuses.  External 
to  the  walls  of  the  sinuses  are  the  muscles  of  mastication  which  j^ass 
downward  to  the  mandible,  passing  thnnigh  these  muscular  tissues  are 
arteries,  veins,  and  nerves. 

The  upper  teeth,  the  alveolar  process  and  the  roof  of  the  mouth  are 
nearly  typical  in  their  formation.  The  space  between  the  tongue  and 
the  roof  of  the  mouth  is  similar  to  that  shown  in  Fig.  301.  Professor 
Donders^  has  spoken  of  this  space  as  acting  somewhat  on  the  same 
principle  as  the  vacuum  chamber  in  an  upper  artificial  denture.  In 
the  cross-section  of  the  tongue  will  Ije  noticed  the  raphe  and  the  blood- 
vessels, etc.,  the  longitudinal  section  of  the  mylohyoid  muscles  is  also 
shown,  with  a  portion  of  the  submaxillary  glands  and  the  integuments 
below  them.  This  section  was  cut  with  the  mouth  closed,  so  the  lines 
of  the  fibers  of  the  mylohyoid  muscles  are  nearly  horizontal  while  in 
Fig.  306,  where  the  mouth  was  opened  when  frozen  and  sectionized,  the 
fibers  descend  downward  and  inward. 

Fig.  303  is  a  similar  section  to  Fig.  302,  giving  an  anterior  view. 
Immediately  below  the  dome  of  the  skull  are  the  meninges.  It  will 
be  seen  that  the  membranes  in  the  centre  pass  downward  to  form 
the  falx  cerebri,  the  lower  edge  of  which  is  attached  to  the  posterior 
portion  of  the  crista  galli.  At  the  top  of  the  falx  cerebri  is  a  V-shaped 
cross-section  of  the  longitudinal  sinus.     The  frontal  lol)es  of  the  brain 

'  Arch,  of  ges.  Physio!.,  Bonn,  1875,  Bd.  x,  S.  91. 


292 


RELATIOX  BETWEEN  MOUTH,   TONGUE  AND  PHARYNX 


show  various  convolutions,  and  it  will  be  noticed  that  they  are  not 
symmetrical.  Immediately  below  the  brain  are  the  inner  walls  of  the 
frontal  sinuses,  passing  well  backward  and  outward  over  the  orbits. 


Superior  longitudinal   sinus. 

Inferior  longitudinal  sinus. 


Falx  cerebri 


Frontal  lobe. 

„  Frontal  bone. 

—  Frontal  sinus  extending  back 
over  the   orbit. 
Levator  palpebrs  sup. 

_-  Rectus  lateralis. 

Optic  nerve. 
Rectus  medialis. 

Anterior   ethmoidal  cells. 

Inferior  rectus. 
Zygoma. 

Temporal  muscle. 
Middle  concha. 
Middle  meatus. 

Inferior  concha. 

Anterior  wall  maxillary  sinus. 

— -  Inferior  meatus 


Air  space  between  the  tongue 
and  roof  of  the  mouth. 

Maxillary  first  molar  tooth. 


Tongue. 


Mandible. 


Mylo-hyoid  muscle. 


Fig.  303. — Frozen  section. 


RELATIOX  BETWEEN  MOT  Til,   TONGUE  AM)  PHARYNX  29:i 

Below  iIk'sc  sinuses  are  the  eross-sections  of  the  orljits  and  e\es,  the 
xarious  recti  nuiscles  of  the  eye,  the  optic  nerve  and  the  ojjluhahiiic 
arteries  and  \eins.  Between  tiie  ()rl)its  are  the  middle  ethmoidal  cells. 
Within  the  nasal  caxil)'  are  cross-sections  of  the  median  wall  and  the 
middle  and  infericjr  concha.  On  each  side  of  the  Icnver  portion  of  the 
nasal  c^ivity  are  the  maxillary  sinuses,  showing  their  posterior  walls. 
The  entire  face  is  more  or  less  compressed,  especially  the  upper  and 
lower  jaws.  The  tongue  has  l)een  forced  out  (jf  shaj^e  1a'  the  i)ressure 
of  the  walls,  showing  that  it  had  not  sufficient  power  to  f(jrce  the 
ah'eolar  j^rocess  outward. 

Fig.  304  is  made  from  a  transxerse  secticjn  of  a  frozen  head.  It  ex- 
hibits a  face  narrowed  and  comi)ressed,  the  maxillary  sinus  of  the  right 
side  is  lacking,  and  the  other  only  rudimentar\'.  It  will  be  ncjticed  that 
while  the  internal  structures  of  the  face  are  \ery  much  c(jm])ressed, 
the  floor  of  the  nose  is  of  fairly  good  width.  The  septum  is  crooked. 
The  arch  of  the  mouth  is  very  narrow  in  proportion  to  the  floor  of  the 
nose.  The  mandible  is  also  narrowed,  consequently  the  tongue  is 
xery  much  compressed  and  out  of  shape  and  is  forced  backxvard  \nU) 
the  phaiynx,  thus  interfering  xvith  respiration,  especially  xvhen  the 
mouth  is  closed.  These  anatomical  structures  are  so  modified  and 
deformed  that  all  the  physiological  functions  are  greatly  interfered 
xvith. 

Normally  the  dorsum  of  the  tongue  lies  against  the  hard  palate, 
but,  according  to  Donders,^  at  the  back  part  it  is  separated  from  the 
soft  palate  by  a  small  space.  Oxving  to  the  xveight  of  the  jaxv,  there  is 
a  negative  pressure  in  this  space  of  2  to  4  mm.  .  .  .  The  jaxv  is  main- 
tained in  position,  not  by  muscular  eft'ort,  but  by  the  pressure  of  the 
air;  so  that,  if  a  tube  from  a  manometer  be  passed  betxx'een  the  tongue 
and  the  palate,  the  manometer  shoxvs  a  slight  negative  pressure  cor- 
responding to  the  weight  of  the  jaxv.- 

Fig.  305  is  from  a  vertical  transverse  section  of  the  same  skull 
used  in  Fig.  304,  also  shoxving  a  very  compressed  condition  of  the 
structures  surrounding  the  oropharynx.  The  uvula  is  txvisted,  the 
tonsils,  the  epiglottis  and  the  larynx  are  out  of  shape  from  pressure 

1  Loc.  cit.  2  Schafer's  Text-book  of  Physiology-,  1900,  ii,  314. 


294  RELATIOX  BETWEEN  MOUTH,  TONGUE  AND  PHARYNX 


Fig.  304. — Vertical  transverse  section  of  a  frozen  head. 


RKLATIO.X   BETWEES   MOUTH,   TUXGLE  AXD  PILIRVXX  2\)o 


Fig.  305. — X'ertical  transverse  frozen  section. 


296  RELATION  BETWEEN  MOUTH,   TONGUE  AND  PHARYNX 

of  the  tongue,  produced,  not  by  a  narrow  floor  of  the  nose,  but  by  a 
narrow  dental  arch.  In  this  case  it  w^ould  be  difficult  to  carry  on  free 
respiration,  and  impossible  to  perform  the  deep  breathing  required 
by  great  exertion.  This  morbid  condition  brings  a  further  congestion 
and  thickening  of  the  mucous  membrane  of  the  nose  and  its  accessory 
sinuses. 

Fig.  306  is  made  from  a  vertical  transverse  section  of  a  frozen  head 
cut  in  the  region  of  the  rami  of  the  mandible  and  the  posterior  portion 
of  the  hard  palate.  The  subject  died  with  the  mouth  open,  and  it  was 
not  closed  before  the  section  w^as  made.  Near  the  anterior  portion 
of  the  pharynx  it  will  be  noticed  that  the  fibres  of  the  mylohyoid  mus- 
cles pass  backward  and  outward  to  the  internal  oblique  lines  of  the 
mandible.  If  those  muscles  are  kept  in  a  state  of  tension,  the  angles 
of  the  mandible  will  be  drawn  toward  each  other  and  thus  tend  to 
contract  the  lower  portion  of  the  face.  Comparison  of  this  illustration 
with  Fig.  302  will  show  great  differences  in  regard  to  these  muscles. 
In  this  specimen  the  palatoglossus  and  the  palatopharyngeus  muscles 
are  placed  on  tension,  narrowing  the  distance  between  the  right  and 
left  tonsillar  spaces.  This  action  of  the  muscles  naturally  influences 
the  narrowing  of  the  face,  as  also  does  the  lack  of  percussive  force 
of  the  lower  teeth  against  the  upper.  When  the  mouth  is  thrown  open, 
the  tongue  leaves  the  roof  of  the  mouth,  thus  giving  passage  for  air; 
the  hyoid  bone  and  all  attached  to  it  is  drawn  downward.  This  also 
puts  the  tongue,  the  hyoid  bone,  the  pharynx  and  other  structures 
that  are  closely  associated  with  them  on  a  tension.  The  muscles  of 
mastication  are  also  stretched. 

Fig.  307  is  a  transverse  section  of  a  skull  that  is  almost  symmetrical, 
showing  the  nasopharyngeal  space  free  from  adenoids.  The  soft  palate, 
the  uvula  and  the  posterior  portion  of  the  tongue  are  in  good  position, 
the  tongue  and  soft  palate  being  close  together.  Below  the  tongue 
and  a  little  to  one  side,  a  cross-section  of  the  hyoid  bone  will  be 
observed  and  below  this  the  hyoid  and  cricoid  cartilages,  showing  the 
inlet  of  the  larynx  and  trachea.  If  the  posterior  portion  of  the  tongue 
be  removed,  the  tonsillar  space  will  be  brought  in  view  as  shown  in 
Fig.  260.      The   section    is   also   made   through    the   brain    case,    the 


RELATIOX  BETWEEN  MOUTH,  TONGUE  AND  PHARYNX  297 


Falx  cerebri. 


Optic  nerve. 


Pcerj-goideus  internus 


Masseter  muscle. 


Palatophar>Tigeus 
Palatoglossus 

Mandible. 


Frontal  lobe. 


Mylo-hyoid 


Tissue   in   portion 
of  orbit. 


Sphenoid  bone. 

Xasal   septum. 
Temporal  muscle. 


N'asal    fossa. 


Soft  palate. 


Masseter   muscle. 


Oro-pharyngeal   space. 


Inferior  alveolar  nerve 
and  vessels. 


Tongue 


Larynx. 


Fig.  306 


298  RELATIOX  BETWEEN  MOUTH,  TONGUE  AND  PHARYNX 


Fig.  307. — 'IVansverss  frozen  section  of  synimclric.il  skull. 


RELATION  BETWEEN  MOUTH,  TONGUE  AND  PHARYNX  299 


Fig.  308. — Vertical  transverse  section  of  narrow  skull. 


300 


RELATIOX  BETWEEX  MOUTH,   TONGUE  AND  PHARYNX 


temporal  muscles,  the  external  and  internal  pterygoid  muscles  and 
processes,  the  internal  maxillary  arteries,  the  rami  of  the  mandible, 
and  the  submaxillary  gland. 

Sup.    longitudinal  sinus. 


Falx  cerebri. 


Corpus  callosum. 
Lateral    ventricle. 
Septum  lucidum. 

Optic  thalamus. 

Lateral  cerebral  fissure 
(fissure  of  Sylvius). 

Temporo  sphenoidal 

lobe. 
Optic  tract. 
Internal  carotid  artery. 
Temporalis  (temporal  muscle). 

Sphenoid  bone. 
Zygomatic  arch. 
Pterygoideus  internus. 

Adenoid  tissue. 

Soft  palate, 
ilasseter  muscle. 

Mandible. 

Pterygoideus  internus. 


Tongue. 


Submaxillary   gland. 


Fig.  309.— Anterior  view  of  Fig.  308. 


RELATION   BETWKES  MOLTII,   TONGUE  AND  rilARVNN 


301 


Levator  veli 

palutini   (Levator 

paiati>. 


Naso-pharynx 


Internal  carotid 
artery. 


Post-pharyngeal 
walL 


Epiglottis. 


Supciior    longitudinal   sinus 

Inferior  longitudinal  sinus, 
l-'alx   cerebri. 

Frontal  lobe. 


Temporo-sphenoidal  lobe. 
Posterior  part  of  orbit. 

Temporalis. 

Temporal  aponeurosis. 


Zygoma. 

Fterygoideus  e.xternus. 
Ramus  of  trandible. 

Soft  palate. 

Heep  portion  of  masseter 


Superior  portion  of 
masseter. 


I'terygoideus  externus. 
Tonsil. 

Palatnpharyngeus. 
PalatoKliissHS. 

Hyoid  bone. 
Thyro-hyoid  muscle. 

Thyroid-cartilage. 

Omohyoid. 

Sterno-cleido-mastoid. 
Cricoid  cartilage. 


Fig.  310. — Frozen  transverse  vertical  section. 


302  RELATIOX  BETWEEN  MOUTH,   TOXGUE  AND  PHARYNX 


Nose. 


Nasal  bone. 

Xasal  Septum. 


of  the  orbit. 


Occipital  bone. 


Straight  sinus. 


firm's 


Fig.  3il. — Horizontal  frozen  section. 


RELATIOS   BETWEEN  MOUTH,   TOXGUE  AM)   PIIARVXX  MO:^ 

Fig.  308  is  a  vertical  transverse  section  (jf  a  narnnv  skull,  showing 
a  compressed  nasal  cavity,  a  deHected  septum,  lack  of  development 
of  the  ethmoidal  cells,  small  ma\illar\-  sinuses  and  narrow  aKeolar 
arches.  The  tongue  is  compressed,  i)art  of  it  jiassing  out  between  the 
jaws  until  it  meets  the  cheek.  When  such  conditions  are  found  it 
usually  indicates  that  the  posterior  nares  are  more  or  less  obstructed, 
either  with  an  osseous  deposit  or  enlarged  adenoid  tissue. 

Fig.  309,  made  from  the  same  skull  as  Fig.  308,  is  an  anterior  view 
of  a  vertical  transverse  section  cut  just  behind  the  posterior  nares. 
Beneath  the  dome  of  the  skull,  the  lateral  ventricles  may  be  seen  under 
the  parietal  lobes  of  the  brain,  which  are  separated  by  the  falx  cerebri, 
extending  downward  to  the  corpus  collosum.  The  temporosphenoidal 
lobes  are  also  seen  with  the  body  of  the  sphenoid  bone  between  them. 
The  most  important  feature  of  this  vsection  in  regard  to  respiration  :s 
that  the  nasopharyngeal  space  has  become  almost  closed  by  the  enlarge- 
ment of  the  adenoid  tissue. 

Fig.  310  is  a  similar  section  to  Fig.  309.  In  the  centre  of  the  oro- 
pharyngeal space,  the  uvula  may  be  seen,  below  which  is  the  post- 
pharyngeal wall,  at  the  bottom  of  this  space,  the  convex  surface  of 
the  epiglottis  is  depicted  and  in  the  upper  and  outer  corners  the  ton- 
sils. To  the  inner  side  of  the  tonsils,  portions  of  the  palatophar^-ngeal 
muscles  are  shown,  while  to  the  outer  side,  and  slightly  covering  the 
tonsils  anteriorally  are  the  palatoglossus  muscles. 

Fig.  311  is  from  a  horizontal  section  cut  through  the  centre  of  the 
orbits,  the  optical  foramen  and  the  optic  nerves,  then  backward  through 
various  tissues  including  the  brain.  This  section  also  exposes  part 
of  the  ethmoidal  cells  connected  with  the  upper  part  of  the  nose. 
X'arious  convolutions  of  the  brain  and  cross-section  of  the  mesen- 
cephalon are  shown,  also  section  of  the  cerebellum,  the  edges  of  the 
tentorium  cerebelli,  the  straight  sinus,  the  falx  cerebri,  and  the  longi- 
tudinal sinus. 


CHAPTER  XIII. 

MODIFICATION   OF   THE   NORMAL   SHAPE   OF   THE 
BONE   THROUGH   ABNORMAL   FORCES. 

The  illustrations  and  descriptions  already  given  demonstrate  that 
there  are  very  marked  variations  in  the  character  of  the  bones  of  the 
face,  and  of  the  sinuses  and  air  spaces  situated  in  and  between  them. 
It  is  evident  that  there  must  be  some  general  principles  underlying 
these  changes. 

Causes  of  Variations  in  Shape. — ^At  the  beginning  of  the  growth 
of  the  embryo,  and  continuing  throughout  life,  there  are  two  forces 
constantly  acting  upon  the  body  which  may  be  described  as  the  intrinsic 
and  extrinsic;  the  former  giving  size  and  bulk  to  the  tissues,  but  con- 
trolled and  modified  by  the  latter,  which,  acting  from  without,  tends 
to  limit  the  growth  and  give  form  to  the  tissues.  If  these  two  forces 
be  normal — that  is,  properly  balanced — in  potential  strength  and 
application  throughout  life,  the  result  will  be  a  normally  developed 
organism;  but  if  these  forces  be  interfered  with  in  any  way,  by  lack  of 
nourishment  or  undue  external  pressure,  the  individual  may  fail  to 
develop  a  normal  physique. 

Deposit  of  Salts  of  Calcium. — If  for  some  reason  there  is  an  insuffi- 
cient quantity  of  salts  of  calcium  assimilated  into  the  bony  tissue, 
the  bones  will  be  soft  and  fail  to  give  proper  shape  to  the  body.  The 
brain-case  in  such  instances  is  apt  to  enlarge  when  the  intrinsic  growth 
of  the  brain  forces  out  the  soft  yielding  structures,  while  on  the  other 
hand  an  overamount  of  salts  of  calcium  will  harden  the  bone,  and 
cause  it  to  resist  the  intrinsic  force  and  prevent  proper  development. 

In  early  life  the  undue  deposit  of  salts  of  calcium  will  solidify  the 
sutures  of  the  brain-case  and  prevent  the  expansion  of  the  brain. 
Microcephalic  skulls  are  sometimes  caused  in  this  way.  By  the  use 
of  the  surgical  engine,  artificial  fissures  have  been  made  in  the  skull, 


DEPOSIT  OF  SALTS  OT  CALCIUM 


305 


which  alKjwed    tiic  l)rain-case  to  expand,  and  thus  enabled  the  brain 
itself  to  enlari;e. 

The  slopes  and  forms  of  the  heads  of  the  various  races  are  influenced 
not  only  by  the  growth  of  the  brain  but  also  by  artificial  means  such 
as  are  practised  by  the  Flathead  Indians  of  North  America  (see  Figs. 
312  and  313)  and  by  the  prehistoric  Indians  of  the  Mesa  Verde'  (see 
Figs.  314-319). 


F"iG.  312. — Side  view  of  a  skull  of  Flathead  North  American  Indian. 

Prof.  Retzius  gives  a  very  interesting  short  description  of  ten  pre- 
historic skulls,  found  b\'  M.  Gustaf  Xordenskiold  in  the  cliff  dwellings 
of  the  Mesa  \'crde,  in  which  he  observes  that  an  artificial  deformation 
of  the  crania  "has  been  caused  in  earh'  infanc>-  by  the  application  of 
pressure  to  the  superior  parieto-occipital  region,  this  jiart  ha\ing  been 
depressed  with  some  flat  object. - 


'  A  good  collection  of  these  skulls  may  be  found  in  the  Wister  Institute,  University  of  Pennsyl- 
vania. 

-  The  Cliff  Dwellers  of  the  Mesa  X'erde,  Southwestern  Colorado,  Stockholm,  1893. 
20 


306 


MODIFICATIOX  OF  NORMAL  SHAPE  OF  BONE 


Fig.  313. — Front  view  of  same  skull  shown  in  Fig.  312. 


Fig.  314. — Side  view  of  a  prehistoric  Indian  of  the  Mesa  Verde. 


I'RI.lIlsrORIC  SKVI.LS 


:m)', 


Fig.  315. — Posterior  view  of  same  skull  as  shown  in  Fig.  314 


Fig.  316. — Anterior  view  of  the  s.ime  skull  as  shown  in  Fig.  314. 


308 


MODIFICATION  OF  NORMAL  SHAPE  OF  BONE 


Fig.  317. — View  of  base  of  skull  shown  in  Fig.  314. 


I"iG.  318. — Side  view  of  prehistoric  skull  from  a  colktliuii  in  Colorado  Springs 


I'KIJIIsroKIC  SKULLS 


3(J'J 


In  Au.uiist,  191 5,  while  \isitinj^  in  Denver,  the  writer  throui^h  the 
courtesy  of  Dr.  A.  II.  Kelcliani  obtained  permissicjn  to  examine  si.xty 
skulls,  some  of  which  had  recent l\  been  exca\ated  fn^m  the  ancient 
clilT  (Kxelliniis  of  the  Mesa  Verde,  and  was  fortunate  in  being  able  to 
secure  i)hotoi;raj)hs  and  measurements  (jf  sexeral  of  these  artificially 
flattened  brach>cephalic  skulls. 

Figs.  314-319,  except  Fig.  318,  are  photograjihs  <jf  i)rehistoric  skulls 
belonging   to  this  collection  in  the  Colorado  State  Museum. 

Fig.  314  is  a  side  view,  showing  result  of  pressure  placed  on  the 
occipitoparietal  region  causing  abnormally  high  dome,  as  evidenced 
by  the  height  and  correspc^nding  diminution  in  the  anteroposterior 
diameter. 


*<^ 


^<t 


Fig.  319. — Side  view  of  a  child's  skull  found  in  the  collection  of  the  Colorado  State  Museum. 

Fig.  315  is  a  posterior  \iew  of  same  skull,  showing  greatest  compres- 
sion in  the  region  of  the  junction  of  the  sagittal  suture  with  the  occipi- 
tal bone  which  has  caused  an  increase  in  its  transverse  parietal  region. 

Fig.  316  is  an  anterior  \iew  of  same  skull,  showing  decided  brachy- 
cephalic  type. 

Fig.  317  is  a  \iew  of  base  of  skull  (314),  showing  the  abnormally  short 
distance  from  the  foramen  magnum  (basion)  to  the  posterior  portion 
of  the  skull.  61  mm.,  measurements  of  the  base  of  this  skull  (see  table, 
page  88). 


310 


MODIFICATION  OF  NORMAL  SHAPE  OF  BONE 


Hir-i^ 


Fig.  320 


■■*^i)  vn 


Fig.  321 

Figs.  320  and  321. — Side  view  of  two  skulls;  Fig.  320  is  of  the  Caucasian  race,  Fig.  321  is  of  the  Fan 

tribe  of  West  Africa.'     They  show  great  differences  in  conformation. 

'  The  Fan  tribe  skull  belongs  to  Professor  E.  T.  Darby's  collection. 


COMJ'AR/SO.X   OF  SKULLS 


ill 


Fig.  318  is  a  side  view  (^f  i)rehist()ric  skull  fn^m  collection  in  Colorado 
Springs,  showing  the  same  marked  de|)ressi(jn  of  the  lambda  and  jdos- 
tero-occipital  regions  produced  In'  artificial  means,  many  of  the  teeth 
are  lost,  some  during  life;  remaining  (jnes  are  strong  but  rather  worn. 

Fig.  319  is  a  side  view  of  a  child's  skull  about  four  or  five  years  of 
age,  showing  the  same  com])ression  in  the  occipital  region.  By  com- 
parison with  the  foregoing  it  will  be  observed  that  this  last  cranium, 
while  presenting  similar  features,  differs  in  the  marked  prominence 
of  the  frontal  region,  esj^ecialh'  on  referring  to  the  skull  of  the  flat- 
headed  Indian  as  shown  in  F'igs.  312  and  313. 


Fig.  322. — Composite  picture  of  the  two  skulls  shown  in  Figs.  320  and  321. 


Where  no  artificial  deformation  exists,  the  brain  by  its  intrinsic  forces 
acting  upon  the  bone  tissue  will  cause  the  skull  to  expand,  according 
to  the  character  of  the  individual  race.  If  the  anterior  lobes  of  the 
brain  are  of  large  size,  the  forehead  will  be  carried  upward  and  forward ; 
if,  on  the  contrar}-,  the  cerebellum  be  large,  the  occipital  region  will 
extend  backward,  while  the  forehead  ma\'  be  low  and  receding.  The 
two  types  are  well  illustrated  in  Figs.  320  and  321.  Fig.  320  is  taken 
from  a  European  skull,  and  Fig.  321  from  the  skull  of  a  Fan  tribe 
negro.  West  Africa.    Fig.  322  is  a  comj^x^site  picture  of  these  two  skulls, 


312  MODIFICATION  OF  NORMAL  SHAPE  OF  BONE 

showing-  their  relative  shapes.  Figs.  323  and  324  give  the  bases  of  these 
two  skulls. 

Prehensile  Type  of  Dentition.. — A  little  study  of  these  specimens 
brings  out  some  features  of  special  interest  to  the  ethnologist.  In  the 
savage  type  a  great  predominance  of  development  in  the  region  of  the 
cerebellum  is  found,  conjoined  with  what  may  be  called  a  prehensile  type 
of  dentition.  It  is  believed  this  type  was  developed  through  continuous 
use  of  the  teeth  in  tearing  off  portions  of  the  substances  which  constitute 
the  food  of  the  savage  races.  The  prehensile  type  of  dentition  is  not 
found  in  the  civilized  races,  and  as  seen  in  the  typical  skulls  the  cere- 
bellum is  much  less  than  in  the  savage.  It  would  appear  reasonable 
that  the  retention  of  the  large  cerebellum — the  original  type — in  the 
latter  results  from  the  low  standard  of  intelligence  evidenced  by  the 
persistence  of  the  food  habit  which  caused  the  prehensile  type  of  den- 
tition. The  two  pictures  in  Figs.  323  and  324  show  that  the  dental 
arch  is  actually  located  further  forward  in  the  skull  of  the  savage  (Fig. 
323)  than  in  that  of  civilized  man  (Fig.  324).  The  anterior  portion  of 
the  zygomatic  process  of  the  maxilla  in  the  savage  is  on  a  line  with  the 
second  molar;  in  the  civilized  man  it  is  on  a  line  with  the  second  pre- 
molar; a  difference  equaling  the  space  of  the  first  molar.  These  obser- 
\ations  are  confirmed  by  a  comparison  of  Fig.  321  from  the  skull  of 
an  African  negro,  and  Fig.  320  from  the  skull  of  a  Caucasian.  It 
would  seem  probable  that  the  lessened  prognathism  of  the  Caucasian 
race  is  one  of  the  principal  causes  of  the  suggested  suppression  of 
the  third  molar.  An  example  of  the  occasional  development  of  a 
rudimentary  fourth  molar  (the  paramolar  of  Bolk)  of  a  prognathous 
savage  is  seen  in  Fig.  325. 

Rudimentary  or  Suppressed  Molars. — There  are  skulls  of  the  Cau- 
casian races  which  have  only  rudimentary  third  molars;  in  some  skulls 
the  third  molar  is  entirely  lacking.  This  has  been  received  by  many 
writers  as  evidence  that  the  third  molar  teeth  are  being  lost  entirely, 
and  as  an  indication  that  men  will  eventually  become  more  or  less 
edentulous.  The  author  is  of  the  opinion  that  the  jaws  and  the  teeth 
of  men  are  as  good  and  fully  formed  at  the  present  time  as  they  were 
three  thousand  or  more  years  ago;  this  does  not  include,  however,  such 


jaiJlMKXTARY  OR  SL  J'J'RK.SSKl)  MOLARS 


:n:i 


jaws  and  teeth  as  are  found  in  the  Meidelhcrp:  or  Sussex  skulls  which 
are  prehistoric  and  supposed  to  be  ain  where  from  two  hundred  thou- 
sand to  a  million  years  old.  If  aiu  ienl  Egyptian  skulls  be  carefully 
examined  the  ru(limentar\'  condition  or  complete  sujii^ression  of  the 
third   molar  will   be  foun<l   (juite  as  freciuently  as  in   skulls  belonging 


Fig.  323  ^'ig.  324 

Figs.  323  and  32-i.— I'nder  view  of  skulls  shown  in  Figs.  320  and  321. 

relati\eh-  to  the  same  class  of  people  today.  This  condition  is  also 
occasionally  found  in  the  North  American  Indians.  There  is  no  diffi- 
culty today  in  finding  jaws  with  good  arches  and  with  thirty-two 
perfectly  developed  teeth,  in  the  living  subject  and  occasionally  with 
supernumerary  or  fourth  molars,  of  which  examj^les  will  be  given. 


314 


MODIFICATION  OF  XORMAL  SHAPE  OF  BONE 


Fig.  326    is   made    from   the    upper  and    lower   jaws   of    a   native 
Australian/  showing  powerful  jaws  and  teeth.      There  seems  to  have 


Fig.  325.— Side  view  of  a  prognathous  skull  of  a  negro  with  eighteen  teeth  in  the  upper  jaw.  The 

roof  of  the  mouth  is  shown  in  Fig.  346. 


'^  -  ■        f  1  urii 

Fig.  326. — Side  view  of  an  upper  and  lower  jaw  of  a  native  Australian. 
'  Belonging  to  the  collection  of  Dr.  E.  C.  Kirk. 


KiniMlA  I  AKV   OR  SIJ'/'R/.SSJJ)   MOLARS 


'Mo 


been  no  (.arics  in  the  tcelh,  hul  tlicrc  is  stronij,  e\idencL'  ol  ij>  (jrrhea 
alveolaris.     The  arches  are  of  ^ood  width. 

Fig.  327  is  made  from  a  mode-rn  manchble  (see  skull  V'lg.  80),  show- 
ing alxnit  as  powerful  a  lower  jaw  as  that  shown  in  Fig.  326  and  the 
teeth  are  good,  without  dera\-,  and  no  evidence  of  p>'orrhea  alveolaris. 

Figs.  328  and  329  are  made  from  .r-ray  pictures  of  a  boy'  sixteen 
years  of  age,  showing  a  right  and  a  left  impacted  mandibular  second 
molar.  Apparently  the  anterior  occluding  surfaces  have  caused  the 
resorption  of  the  posterior  njots  of  the  first  molars;  there  seems  to  be 
no  development  of  the  third  molars,  also  no  evidence  that  the  lower 
second  premolars  have  developed.  The  roots  of  the  deciduous  teeth 
show  evidence  of  resorption,  although  there  are  no  permanent  teeth 
inciting  this  acti(jn. 


I    '.  A     X 


Fig.  327. — Side  view  of  a  modern  heavy  mandible. 

Fig.  330  gives  an  .v-ray  picture  of  the  ui)i)er  and  lower  jaws.  There 
is  no  evidence  of  the  development  of  the  left  third  molars  or  of  the 
second  premolars,  but  as  in  the  case  of  Figs.  328  and  329,  the  resorp- 
tion of  the  roots  of  the  deciduous  teeth  had  taken  place  without  the 
action  of  the  permement  teeth. 

Fig.  331  is  an  .v-ray  picture,  showing  teeth  of  the  right  side  ot  the 
same  jaws  as  Fig.  330,  the  third  molar  is  de\eloping  while  the  second 
maxillary  deciduous  molar  has  been  shed  without  the  premolar  to  take 
its  place.  It  will  also  be  noticed  that  there  is  no  development  of  the 
maxillary  third  molar. 

1  Taken  from  a  patient  of  Dr.  T.  G.  Barnes,  Springfield,  Mass. 


316 


MODIFICATIOX  OF  XORMAL  SHAPE  OF  BONE 


Fig.  i29 
Figs.  328  anr]  329. — -Y-ray  pictures,  showing  riglit  and  left  impacted  second  molars. 


RiniMEXTARV  OR  sr I'/'RESSED  MOLARS 


'M7 


Fi^.  332  is  an  .v-ra\'  picture  of  a  lixinj;  i)atienl  about  t\\X'nt\  >ears 
of  age,  sliowing  a  deciduous  mandibular  second  molar,  in  jiosition, 
there  is  no  second  i^remoiar  (leveloi)in;^  to  take  its  i)lace;  it  will  be 
noticed  that  the  roots  of  the  deciduous  tooth  ha\e  been  resorbed  to 
a  great  extent. 


Fig.  330. — J^-ray  of  upper  and  lower  jaw.    There  is  no  evidence  of  ttie  development  of  the  leli  third 

molar  or  of  the  second  premolars. 

Fig.  333  is  an  .v-ray  i)icture  of  an  ancient  Egyptian  mandible,'  show- 
ing the  retention  of  a  second  deciduous  molar  and  the  absence  ot  the 
developing  second  ])rem()lar  similar  to  the  missing  premolars  in  Fig.  ;'-^;^2. 

1  Belonging  to  the  collection  of  Dr.  \\.  (".  Kirk". 


318 


MODIFICATIOX  OF  XORMAL  SHAPE  OF  BONE 


Figs.  334  and  335  are  .v-ra>'  pictures  showing  two  impacted  man- 
dibular third  molars  in  prehistoric  mandibles.  These  two  bones  were 
found  near  Tuckerton,  N.  J.,  and  are  supposed  to  have  belonged  to 
a  race  of  people  inhabiting  this  region  before  the  North  American 
Indians. 


Fig.   331. — A'-ray  picture  of  a  modern  jaws. 

Figs.  336  and  337  are  illustrations  made  from  the  left  outer  side  and 
the  right  inner  side  of  a  mandible  of  a  modern  skull  show^ing  tw^o 
impacted  third  molars;  the  left  one  is  nearly  horizontal,  while  the 
right  one  is  badly  "locked"  under  the  posterior  portion  of  the  second 
molar. 


RU DIMES  r.  I  A'  1  ■   OK  SL  P PRESS KI)  MOL.  1  A'.V 


■M\) 


Fig.  33<S  is  iiiatle  from  an  .v-ra>'  picture  of  llie  same  niandil)le  as 
shown  in  Figs.  336  and  337.       In  this  way  the  position  of  the  roots  is 


Fig.  332. — A'-ray  of  modern  jaws  showiiij;  deciduous  molar.     (A'-ra\-  !)>•  Dr.  Pancoast.) 


Fig.  333. — -Y-ray  picture  of  an  ancient  Egyptian  mandible.      (A'-ray  by  Dr.  Pancoast.) 


320 


MODIFICATION  OF  NORMAL  SHAPE  OF  BONE 


illustrated,  shewing  considerable  thickening  of  the  tissue  around  the 
roots. 

Fig.  339  is  an  .v-ray  picture,  showing  a  developing  lower  rudimen- 
tary fourth  molar  in  a  modern  mandible.^  There  is  strong  evidence 
that  a  pathological  condition  existed  in  the  tissue  surrounding  the 
first,  second  and  third  molar  teeth,  especially  the  second  and  third. 


Figs.  334  and  335. — X-ray  picture  of  two  prehistoric  mandibles,  showing  impacted  mandibular 
third  molars.     (X-ray  by  Dr.  Pancoast.) 

Fig.  340  is  from  a  photograph  of  a  living  subject,  showing  five 
maxillary  incisors. 

Fig.  341  is  from  an  .x-ray  picture, ^  showing  five  erupted  deciduous 
and  five  unerupted  permanent  incisors  in  the  mandible  of  a  living  person. 

1  Belonging  to  the  collection  of  Dr.  Kirk's.  ^  X-ray  picture  loaned  In-  Dr.  Blum  of  New  York. 


IWDIMEXTARV  OK  Sir  PRESS  ED  MOLARS 


321 


Figs.  336  and  337. — Two  halves  of  the  same  iiiaiuhblc,  showing  two  impacted  third  molars. 


oi        ^^^''  ^^^' — '^''^^y  picture  showing  two  impacted  third  mandibuhir  molars. 


322  MODIFICATION  OF  NORMAL  SHAPE  OF  BONE 


Fig.  339. — A'-ray  picture  showing  impacted  lower  rudimentary  fourth  molar. 


Fic.  340. — Photograph  showing  five  maxillary  incisors. 


Fig.  341. — Z-ray  showing  five  deciduous  and  five  permanent  incisors. 


.S  L  TERX  LMERA  R  \ '  FREM  OL.  1  A'   J  KJ:  J  U 


323 


SUPERNUMERARY  PREOMLAR  TEETH. 

It  is  not  iiiuisual  to  lind  t'Xtra  prcniolar  teclh  in  ihc  maxilla  or 
mandible.  Dr.  Robert  II.  Iv\-  has  reported  a  case  of  si.\  mandibular 
prenKjlars,  <Hie  of  which  was  impacted.'  Dr.  Inglis  reports  a  "case  of 
se\en  lower  l)icusi)ids,  two  supernumeraries  in  i)lace  and  one  erupting. 
The  patient  has  also  two  sui)ernumerar\'  upi)er  central  incisors  dis- 
placing the  centrals  i)n)per,  >et  closely  resembling  them."- 


FlG.  342. — Plaster  cast,  showing  six  premolars  lecth. 

Dr.  Hopewell-Smith  mentions  a  case  of  a  negro  having  a  super- 
numerary premolar  on  each  side  of  the  mandible.^ 

Dr.  A.  H.  Ketcham,  of  Denver,  very  kindly  loaned  the  cast  of  a 
patient's  mouth  from  which  Fig.  342  was  made,  showing  three  pre- 
molars on  each  side  of  the  maxilla. 

Fig.  343,  344  and  345  were  made  from  a  clinical  patient  about 
twenty-four  years  of  age,  at  the  Evans  Dental  Institute.  Examina- 
tion showed  that  the  mandibular  first  molars  had  been  extracted  on 
both  sides  to  give  room  for  other  teeth  that  were  in  j)r()cess  of  eruption. 

'  Dental  Cosmos,  June,  1915,  p.  670. 

-  Dental  Pathology  and  Therapeutics,  fifth  edition,  p.  282. 

'  Dental  Anatomy  and    Phys  oiogy,  1913,  p.  215. 


324 


MODIFICATIOX  OF  XORMAL  SHAPE  OF  EOXE 


The  four  incisors  and  two  canine  teeth  were  well  developed  and  in 
normal  positions.  Fig.  343  is  an  .v-ra}.'  of  the  right  side  of  the  upper  and 
lower  jaws.  Three  premolars  in  fairly  good  position  may  be  seen  in 
the  mandible,  also  a  fourth  impacted  premolar.     The  lingual  cusp  of 


Fig.  343. — X-ray  showing  four  premolars.      (A^-ray  by  Dr.  Pancoast.) 


the  second  premolar  is  not  well  formed  (see  Fig.  345),  the  other  two, 
however,  have  well-shaped  crowns. 

Fig.  344  is  made  from  the  left  side  of  the  face,  the  space  between  the 
last  premolar  and  the  sec(^nd  molar  indicates  that  the  first  molar  had 


.s77v:a'.\7  .i//:a'.i AT  i'i<i:\H)i.M<  Ti:i:ni 


825 


been  extracted.  There  are  three  prt'inohirs  in  ix)siti(>n  with  well-formed 
crowns  and  an  inii)aeted  tooth  ma>'  be  seen  between  the  llrst  and  second 
premolar  to  which  no  better  name  can  be  given  than  extra  premolar, 
making  eight  premolars  in  the  mandible. 


Fig.  344. — A'-ray  showing  four  premolars.      (A'-ray  hy  Dr.  Pancoast.) 

Fig.  345  is  made  from  a  j^laster  cast  of  the  occluding  surface  of  the 
mandibular  teeth,  showing  that  the  incisors  and  canines  are  quite 
normal  in  position  and  shape,  five  premolars  show  fairh-  good  crowns, 
while  a  sixth  premolar  on  the  right  side  is  deformed. 

It  will  be  noticed  in  this  illustration  that  there  are  two  elevations 


526 


MODIFICATION  OF  NORMAL  SHAPE  OF  BONE 


on  the  inside  of  the  jaw,  above  the  sublingual  fossae,  indicating  the 
position  of  the  impacted  premolars  as  shown  in  the  two  x-ray  pictures. 


Fig.  345. — Plaster  cast  of  lower  jaw  from  the  same  as  shown  in  X-ray,  Figs.  343  and  344. 


Fig.  346. — Palatal  aspect  of  the  maxillary  teeth  and  bone,  from  same  skull  shown  in  Fig.  325 

Fig.  346  vshows  the  under  surface  of  the  upper  jaw  seen  in  Fig.  325 
with  a  rudimentary  fourth  molar  on  each  side  of  the  arch. 


Si  TERM  M ERA RV  I'RKMOLAR   TEETH 


327 


Figs.  347  and  348  show  the  uiukT  surfare  of  two  upper  jaws,  the 
occkiding  surface  of  the  teeth,  and  their  rehitive  size.  Fig.  348  is  about 
the  nornuil  size,  while  V\g.  347  is  very  much  larger.     In  Fig.  347  there 


Supernumerary  tooth 


Supernumerary  toolh 


Fig.  348 
P^iGS.  347  and  348.— View  of  two  upper  jaws.     The  occluding  surfaces  of  the  teeth  and  roofs 
of  the  mouths,  and  the  great  difference  in  relative  size,  are  well  shown.    Fig.  347  has  two  rudimentary 
fourth  molars. 

are  two  fourth  rudimentary^  molars,  one  in  the  line  of  the  arch  and  one 
on  the  buccal  side  of  the  second  molar. 

Fig-  349  is  a  \iew  of  the  palatal  surface  of  an  upper  jaw,  showing 
the  occluding  surfaces  of  the  teeth,  with  two  supernumerar\-  teeth 
situated  on  the  l)uccal  sides  of  the  second  molars. 


328 


MODIFICATION  OF  XORMAL  SHAPE  OF  BOXE 


Supernumerary  tooth 


Supernumerary  tooth 


Fig.  349. — \'ie\v  of  the  roof  of  the  mouth  and  occluding  surfaces  of  the  teeth  from  an  ordinary  sized 
upper  jaw,  showing  two  rudimentary  fourth  molars. 


Fig.  351 
Figs.  350  and  351. — Two  mandibles,  Fig.  350  from  the  Fan  tribe.  West  Africa,  Fig.  351  from  a 
Caucasian,  showing  the  difference  in  the  position  of  the  teeth  in  relation  to  the  ramus,  the  mental 
foramen,  and  the  symphysis. 


SL  I'KRX L  MER. \RV   RRLMOL.  1  A'   TEETH  329 

Comparison  of  Mandibles  of  a  Caucasian  and  an  African  Negro. — 
Figs.  350  and  351  affords  a  coiiiiKirison  hetwcL-n  the  niandihlcs  of  the 
Caucasian  and  of  the  Fan  tribe  negro  (West  Africa).  Thex'  were 
photographed  ii|)()ii  the  same  phite,  showing  their  rehitixe  size  and 
shape.  The  teeth  and  alveolar  process  in  Fig.  350  ha\e  been  carried 
much  further  forward  than  those  in  Fig.  351.  In  Fig.  350  the  third 
molar  is  in  advance  of  the  ramus,  while  in  Fig.  351  the  third  molar, 
to  a  great  extent,  is  posteri(jr  to  the  anterior  margin  of  the  ramus, 
the  difference  being  about  the  width  of  a  molar  tooth.  In  Fig.  350 
the  mental  foramen  is  beneath  the  hrst  molar,  while  in  Fig.  351  it  is 
beneath  the  interspace  between  the  two  premolars,  again  a  difference 
of  about  the  width  of  a  molar  tooth. 


CHAPTER  XIV. 
THE    INFLUENCE   OF   MUSCULAR  ACTION. 

After  the  birth  of  the  child,  muscular  action  and  various  forces 
have  direct  influence  over  changes  in  the  shape  of  the  bones,  according 
to  the  following  rules: 

The  normal  application  of  the  forces  affecting  developing  bone 
results  in  normal  development  of  the  form  of  the  bone.  Their  abnormal 
application  under  the  same  circumstances  results  in  the  development 
of  abnormally  formed  bone.  Abnormal  application  of  forces  to  the 
bone  in  adult  life  will  also  change  and  modify  the  shape  and  character 
of  the  bone  tissue.  The  changes  which  may  be  caused  by  the  applica- 
tion of  abnormal  forces  to  the  developing  individual  are  well  illustrated 
by  the  disfigurements  resulting  from  the  tight  bandages  put  upon  the 
feet  of  Chinese  girls  of  the  higher  class,  the  use  of  corsets  to  contract 
the  waists  of  the  European  women  of  the  analogous  class,  and  the 
flattening  of  the  skulls  of  certain  Indians  of  North  America  by  binding 
boards  upon  the  heads,  of  the  children.  Fig.  312  gives  a  side  view  of 
one  of  these  Indians.  Fig.  313  gives  a  front  view,  showing  that  by 
the  compression  of  the  frontal  region  downward  the  skull  has  been 
extended  laterally. 

The  modification  of  the  bones  by  abnormal  muscular  action  is  well 
illustrated  by  the  changes  found  in  persons  suffering  from  true  or 
false  ankylosis  of  the  temporomandibular  articulation.  The  illus- 
trations which  follow  are  taken  from  a  patient  and  from  the  bones  of 
two  skulls. 

False  Ankylosis. — Fig.  352  is  from  the  photograph  of  a  patient 
who  has  been  suffering  from  false  ankylosis.  Judging  from  the  general 
outline  of  the  face,  with  its  protruding  lips  and  receding  chin,  one 
might  be  inclined  to  classify  the  individual  as  a  degenerate,  but  the 


FALSE  A  SKY  LOS  IS 


331 


writer  l)elieves  tlial  this  i)iclurc',  and  others  to  folhnv,  sliow  thai  this 
is  a  typical  face  beloniiing  to  those  who  ha\e  or  who  have  had  ank\  - 
losis  of  the  jaw.  cither  true  or  false.  This  i)atient  has  suffered  from  a 
false  a!ik\  losis  since  about  nine  \ears  of  age. 

Fig.  353  is  taken  from  the  right  side  of  the  same  face,  showing  a  scar 
extending  ui)ward  and  backward  from  the  angle  of  the  mouth  to  the 
region  of  the  external  acoustic  meatus.     The  scar  was  i)roduced  b\-  a 


F"iG.  352. — Characteristic  appearance  in 
the  region  of  the  lower  jaw  in  long-standing 
ankylosis. 


Fig.  353. — Opposite  side  of  face  of  Fig.  i52, 
showing  scar  caused  by  a  gunshot  wound,  the 
effects  of  which  produced  false  ankylosis. 


gunshot  wound.  The  shot  in  passing  severed  the  masseter  muscle 
as  well  as  a  portion  of  the  buccinator.  In  the  healing  of  the  parts 
false  bands  of  cicatricial  tissue  were  formed,  extending  from  the  lower 
jaw  to  the  zygoma  and  the  zygomatic  arch.  The  pterygomandibular 
ligament  was  also  shortened,  thus  preventing  the  jaws  from  being 
opened.  The  treatment  for  the  false  ankylosis  consisted  in  cutting  the 
false  bands  and  using  the  mouth-gag  with  a  screw  to  break  up  the  false 
ligaments.     The  operator  was  afterward   assisted   by   the   patient   in 


332 


IXFLUEXCE  OF  MUSCULAR  ACTION 


forcing  the  jaws  asunder,  as  shown  in  Fig.  354.  The  main  object  in 
using  the  apphance  was  to  stretch  the  temporal  and  masseter  muscles 
of  both  sides.  In  a  few  weeks  the  patient  could  open  the  jaw^s  without 
the  appliance,  as  shown  in  Fig.  355.  There  was  at  this  time  sufficient 
impro\ement  to  permit  of  the  mastication  of  food  and  the  proper 
care  of  the  teeth.     The  condition  has  since  been  further  improved. 


Fig.  354. — Application  of  jack-screw  for  forcing  the  mouth  open  in  false  ankylosis. 

Other  causes  of  false  ankylosis  are:  Ossification  of  the  pterygo- 
mandiljular  raphe,  myositis  ossificans  affecting  the  masseters,  pterygoid 
or  buccinatfjr  muscles. 

Typical  Ankylosed  Mandible. — In  cases  of  true  ankylosis  of  the 
jaw,  especially  those  of  long  duration,  certain  changes  in  the  form  of 


TYriCAL   .WKVLOSIJ)   M.WDIIiLE 


333 


the  nian(lil)l('  arc  not ici-ahli',  not  only  on  the  affVclcd  side*  wlicii  the 
ank>  losis  is  unilateral,  but  also  on  the  o|)i)osite  side.  The  eharaeter 
of  these  chaniies  is  well  shown  in  I^^i.^s.  356  and  ,^57.  I'"i^.  356  is  a  view 
of  the  unankylosed  side  of  a  Ixpical  case  of  true  unilateral  ankylosed 
jaw.  The  condxloid  ])rocess  is  shortened  and  its  articulating;  surface 
is  chani^ed.      Instead  ol    heinu   rounded  at    the  top  it   has  more  of  the 


¥iv,.  355. — Results  of  trcatnu'iit  for  false  ankylosis. 

shape  of  a  (lOthic  arch.  ThrouL;h  this  shortening  of  the  conch  loid, 
the  coronoid  process  is  apparently  elongated.  The  angle  of  the  man- 
dible is  also  elongated  so  that  it  forms  a  projecting  point,  and  tin-  base 
of  the  bone  under  the  mental  foramen  is  considerabh-  thickened. 
The  mental  i)rocess  is  much  diminished  in  size.     There  is  no  loss  of 


>o4 


IXFLUEXCE  OF  MUSCULAR  ACTION 


bone,  but,  by  the  operation  of  causes  to  be  referred  to,  a  metamorphosis 
has  been  induced  whereby  the  base  of  the  bone  has  been  thickened 
at  the  expense  of  the  mental  process.  Owing  to  the  same  causes,  the 
base  of  the  bone,  between  the  angle  and  a  point  vertically  underneath 


\ 


Fig.   356  — Unankylosed  side  of  a  jaw  having  a  true  unilateral  ankylosed  mandibular  articulation. 


Fig.  357. — The  ankylosed  side  of  Fig.  356. 

the  canine  teeth,  is  deeply  concave  in  outline  instead  of  being  nearly 
straight,  as  in  the  normal  jaw. 

Fig-  357  is  taken  from   the  opposite  side  of  the  face  in  Fig.  356, 
showing   the  condyloid   process   completely  changed;  it  is  broadened 


TRUK  AX  KY  IDS  IS 


335 


out,  and  is  sharjil)'  serrated  on  the  articulating^  surface.  The  articu- 
lating surface  of  the  nian(Hl)uhir  fossa  is  also  changed  to  correspond 
to  that  of  tlie  condxle  with  which  it  was  interlocked.  The  angle 
of  the  jaw  on  ihis  side  is  much  more  changed  than  on  the  opposite 
side,  causing  a  deep  depression  in  the  region  of  the  facial  notch.  The 
lower  jaw,  beneath  the  mental  ])rocess,  is  fuller  anrl  more   roughened 


Fig.  358. — A  skull  with  a  true  ankylosis  of  the  mandibular  articulation  on  the  opposite  side. 


and  the  mental  process  more  concave  than  on  the  opposite  side.  The 
concavity  of  the  base  of  the  jaw  and  the  elongated  angle  are  readily- 
seen  in  the  picture  of  the  living  subject  (Fig.  360). 

True  Ankylosis. — Fig.  358  is  from  a  skull  with  a  complete  or  true 
unilateral  ankylosis  of  the  jaw,  taken  from  the  unank\losed  side. 

Fig.  359  shows  the  ankylosed  side.  The  lower  jaw  closely  resembles 
that  shown   in   Fig.  357,   in  the  descending  angle,   the  receding  chin, 


386  INFLUENCE  OF  MUSCULAR  ACTION 

etc.  In  all  cases  of  prolonged  ankylosis  it  becomes  evident  that  there 
is  cause  for  the  changes  observed  in  the  form  of  the  bones.  The  muscles 
of  mastication,  i.  e.,  those  which  elevate  the  lower  jaw — are  inactive, 
while  those  which  assist  in  depressing  the  mandible  become  more  and 
more  active  in  their  work,  in  an  endeavor  to  overcome  the  fixation 
of  the  mandibular  articulation.  By  their  action  the  lower  jaw,  from 
the  symphysis  to  the  angle,   becomes  modified  in  proportion  to  the 


Fig.  359. — View  of  the  ankylosed  side  of  Fig.  358. 

contraction  of  the  depressing  muscles  of  the  jaw.  Anteriorly  there 
are  the  two  genioglossus,  the  sternothyroid,  the  sternohyoid,  the 
digastricus,  the  omohyoideus,  and  the  platysma,  all  of  which  are 
abnormally  active.  Their  action,  without  the  normal  compensating 
factor  of  the  mandibular  motion,  brings  about  in  time  the  changes 
noted. 

Fig.  360  is  a  picture  of  the  patient  shown  in   Figs.  352  and   353, 
showing  an  endeavor  to  open  the  mouth   by  the  assisted  action  of  the 


CIIAMiKS  L\    THE  MAMJIHL  LM<  A  RJTCL  LATIU.X 


■.va: 


muscles.  It  illustrates  the  \ari()us  nuiscles  under  si)asni(Klic  acti{Jii, 
inclicalini;  how  their  frecjuent  use  under  such  conditions  ma\'  cause 
alterations  in  the  form  of  the  bone. 

Changes  in  the  Mandibular  Articulation  other  than  by  Ankylosis. — 
Teeth  becoming  diseased  or  lost  on  one  side  of  the  jaw  cause  changes 
in  the  forms  of  the  various  bones,  throu.i>h  the  necessity  of  masticating 
on  the  opposite  side  of  the  mouth,  and  the  consequent  use  oi  the  jaws 
in  an  abnormal  manner.  In  this  way  i^reat  alterations  can  be  made 
in   the  mandibular  articulation,  and  in  one  or  both  man(lil)ular  fossa*. 


Fig.  360. — The  action  of  the  tlcprcssor  muscles  of  the  iiiaTulil)le  in  ank>losis. 

The  articular  tubercle  may  be  entirely  lost  by  resorption.  The  places 
of  attachment  for  the  muscles  of  mastication,  as  the  coronoid  i:)rocess, 
the  outer  surface  of  the  ramus,  the  angle  of  the  jeiw,  etc.,  become 
roughened  and  enlarged  on  the  side  in  use,  and  smooth  and  lessened 
on  the  unused  side.  The  spaces  where  the  muscles  have  their  origin, 
such  as  the  external  plate  of  the  pterygoid  process,  the  under  surface 
of  the  zygomatic  arch,  and  the  temporal  ridge  of  the  skull,  will  also 
become  enlarged  on  one  side  and  lessened  on  the  other. 

Several  illustrations  are  here  gi\en   to  show  the  changes  brought 
about  by  the  loss  of  teeth  and  changed  position  of  occlusion. 

22 


338 


IXFLUEXCE  OF  MUSCULAR  ACTION 


Fig.  361  is  a  view  of  the  articulation  of  the  left  side  of  the  skull  of 
an  aged  person  who  had  lost  all  the  teeth  except  three  in  the  upper 
jaw  and  three  in  the  lower  jaw.  They  were  not  opposite  to  one 
another  in  normal  occlusion.  In  order  that  the  cutting  or  grinding 
surfaces  of  these  teeth  could  come  into  occlusion,  the  left  side  of  the 
jaw  had  to  be  carried  forward,  bringing  the  condyloid  process  of  that 
side  upon   the   articulating   tubercle,  while  the  right  side  remained   in 


Fig.   361. — Modification  of  the  left  mandibular  articulation  through  the  jaw  being  forced  forward 
in  mastication  in  order  to  bring  the  remaining  teeth  in  occlusion. 

a  nearly  normal  position,  as  shown  in  Fig.  362.  Upon  close  examina- 
tion of  the  condyle  of  the  left  side,  it  is  found  to  be  flattened  out, 
probably  because  of  coming  in  contact  with  the  articular  tubercle, 
thus  moving  the  point  of  articulation  forward,  or  "jumping  the  bite." 
The  tubercle  or  eminence  is  flattened  also.  The  forces  of  mastication 
of  the  left  side  were  but  little  used,  and  accordingly  the  places  of  origin 
and  insertion  of  the  muscles  of  that  side  are  much  less  marked  than  the 
normal;   while  on   the   right  side,   upon  which   alone  the  function  of 


CHAXCKS  T\   Till']  .\f.\.\/)f/U/..\R  ARTICULATION 


339 


Fig.  362. — The  ri.i>;ht  mandibular  articulation  from  skull  shown  in  the  i^recedinK  photograph,  where 
the  condyloid  process  has  not  been  carried  forward. 


Fig.  363.— Right  side  of  a  skull.    See  mandible,  Fig.  9. 


840 


IXFLUEXCE  OF  MUSCULAR  ACTION 


mastication  was  performed,  the  muscles  were  thus  overworked,  and  the 
places  of  attachment  and  of  their  origin  and  insertion  are  strongly- 
marked  in  consequence. 

Fig.  363  gives  a  view^  of  the  right  side  of  a  skull.  It  w411  be  seen 
that  the  three  molars  and  one  premolar  of  the  maxilla  are  missing. 
In  the  mandible,  all  the  teeth  except  the  first  and  second  incisors  have 
been  lost. 


Fig.  364. — Left  side  view  of  the  same  skull  as  Fig.  363,  showing  the  condyloid  process,  articulating 
on  the  squamous  portion  of  the  temporal  bone  and  partly  on  the  great  wing  of  the  sphenoid  instead 
of  the  mandibular  fossa. 

Fig.  364  gives  a  view  of  the  left  side  of  the  same  skull,  showing  a 
few  upper  and  lower  teeth  in  occlusion.  The  remarkable  characteristic 
is  the  abnormally  small  ramus,  and  portion  of  the  body  of  the  bone. 
The  condyloid  process,  instead  of  articulating  in  the  mandibular  fossa, 
articulated  partly  on  the  squamous  portion  of  the  temporal  bone,  and 
partl>'  on  the  great  wing  of  the  s])henoid.  There  seem  to  be  two  ways 
in  which  this  deformity  could  occur.     One  is  by  the  lack  of  growth  in 


CI/.WCFS   /.\     /■///■:   M.WDf/ilLAR   .1  A'/VCTAJ  77r>.V 


:'>41 


the  raimis  aiid  hods  of  boiu';  the  otluT  theory  is  that  the  bone-  urew 
to  its  normal  size  (as  there  is  evidence  of  its  having  articulated  in  the 
niandil)iihir  fossa),  when  an  atrophied  condition  may  have  occurred 
wiiich  reduced  the  size  of  the  ramus  and  part  oi  the  body;  in  order  to 


Fig.  365. — Under  view  of  the  articulation  ol  ihc  niaiidilile  as  shown  in  Fig.  364. 
See  base  of  skull,  ¥\g.  93. 

keej)  up  occlusion  of  the  teeth,  the  condyloid  process  mo\ed  forward, 
first  articulating  on  the  articular  tubercle,  and  as  the  atrophy 
progressed,  moving  still  forward  to  keep  the  occlusicjn.  until  the 
condxloid  i)rocess  reached  the  position  shown  in  the  illustration. 


CHAPTER  XV. 

HYPERTROPHY  OF  THE  GUMS  AND  ALVEOLAR  PROCESS. 

Abnormal  growth  of  the  bone  may  produce  almost  the  same 
effect,  so  far  as  appearances  go,  as  the  modification  caused  by  abnormal 
muscular  action.  In  Februar}^  1893,  Dr.  J.  W.  Hisey,  of  Cleveland, 
brought  to  the  Hospital  of  Oral  Surgery  a  boy  of  fifteen  years.     The 


Fig.  366. — From  the  photograph 
of  a  lad  suffering  from  hypertrophy 
of  the  gums  and  alveolar  process. 


Fig.  367. — Tissue  removed  from  upper  jaw  of 
patient  shown  in  Fig.  366. 


boy  was  well  developed,  bright,  intelligent,  and  well  educated.  He 
was  afflicted  with  the  most  remarkable  case  of  hypertrophy  of  the 
gums  and  alveolar  process  that  the  writer  has  seen  recorded.  The 
case  was  operated  upon  by  the  late  Professor  Garretson  and  the  writer, 
February  17  and  March  11,  1893.^ 


'  A  full  description  of  the  operation  will  he  found  in  the  Dental  Cosmos,  June,  1893. 


IIVPKRTROP/IV  OF  aCMS  AM)  A/AKOLAR  PROCESS 


343 


Fig.  366  is  froiu  a  photograph  of  the  lad  taken  before  the  operation. 
Similarh'  to  the  first  picture  shown  in  the  ankylosis  series,  this  boy 
a|)i)ears  to  ha\e  an\thin,i^  l)iit  an   intellii;ent  face.     On  February   17, 


Fig.  368. — Tissue  removed  from  the  lower  jaw  of  patient  shown  in  Fig.  366. 


Fig.  369. — From  a  photograph  taken  three  weeks  after  the  removal  of  the  tissue  in  Figs.  367  and  368 

Professor  Garretson  decided  that  it  was  best  to  open  the  upper  lip  at 
the  median  line  and  carr>-  the  incision  around  to  the  alae  of  the  nose. 
By  the  aid  of  the  surgical  engine  and  other  instruments,  the  portion 


344  HYPERTROPHY  OF  GUMS  AND  ALVEOLAR  PROCESS 

shown  in  Fig.  367  was  removed  from  the  upper  jaw.  It  was  thought 
best  not  to  remove  the  abnormal  tissue  from  the  lower  jaw  at  this 
operation,  so  it  was  delayed  until  March  11,  when  the  mass  of  tissue 
shown  in  Fig.  368  was  removed  from  the  lower  jaw.  This  last  was 
accomplished  without  cutting  the  lip. 

Fig.  369  is  from  a  photograph  taken  about  April  28,  seven  weeks 
after  the  second  operation;  the  parts  were  thoroughly  healed  and  the 
general  health  of  the  patient  was  good.    He  experienced  less  difficulty 


Fig.  370. — From  a  photograph  six  years  after  the  operation  upon  the  person  represented  in  Fig.  330. 

in  articulating  than  previous  to  the  operation,  and  the  improvement 
in  his  speech  and  general  appearance  was  very  marked. 

Artificial  dentures  were  supplied  in  due  time. 

Fig.  370  is  made  from  a  photograph  taken  six  years  after  the 
operation.  To  judge  from  this,  the  young  man  certainly  does  not  look 
like  a  degenerate.  The  operation  has  evidently  made  a  tremendous 
imi)r(n'ement  in  his  appearance,  and  it  seems  to  be  conclusively 
demonstrated  that  Professor  Garretson  was  right  in  his  judgment. 


CHAi'ri:k  XVI. 
Till-:    RKLATIOX    OV   TllK   TWO   JAWS. 

The  Relation  of  the  Upper  and  Lower  Jaws  Varies  Throughout 
Life. — There  is  also  a  difference  in  tlieir  relative  time  of  (le\eloi)nient. 
The  lower  jaw  is  developed  slii'htl>'  in  advance  of  the  uj^per  one  and  is 
formed  trom  two  processes  or  buds,  the  upper  jaw  bein^  formed  from 
four  processes  or  buds — two  from  the  sides  and  two  from  ab(ne. 
Occasionally  these  four  processes  fail  to  completely  unite.  This  lack 
of  union  varies  from  a  slight  cleft  palate  or  hare-lip  to  a  double  cleft 
i:)alate  and  double  hare-lip.  In  a  few  very  exceptional  cases  there  has 
been  an  entire  lack  of  union  of  these  parts,  leaving  the  mouth,  nasal 
cavity,  and  orbits  as  one  common  cavity.  Various  theories  have 
been  advanced  for  this  lack  of  union,  the  most  prominent,  perhai)s, 
being  that  of  malnutrition  of  the  parts  during  the  time  when  the 
union  should  take  place.  While  agreeing  that  malnutrition  is  probably- 
largely  responsible,  the  writer  offers  as  a  plausible  explanation  of  the 
manner  of  its  operation  the  idea  that  as  the  lower  jaw  is  formed  in 
advance  of  the  upper  one,  when  undue  pressure  is  exerted  upon  it,  it 
is  forced  in  between  the  four  processes  forming  the  upper  jaw,  thus 
mechanically  preventing  them  from  coming  together. 

The  normal  position  of  the  fetus  /;/  iitero  is  such  that  the  weight 
of  the  entire  fetal  body  could  be  thrown  upon  the  vertex,  the 
l^ressure  thus  exerted  would  tend  to  force  the  mandible  into  contact 
with  the  sternal  region  and  compress  the  forming  jaws  together.  The 
relatively  advanced  development  of  the  mandible,  as  compared  with 
that  of  the  forming  maxilla,  would  under  the  circumstances  referred 
to,  and  especially  in  cases  of  low  nutritional  standard,  interfere  with 
the  normal  closure  of  the  brachial  arches  and  tend  to  produce  a  per- 
manent coloboma. 

If  an  examination  be  made  of  a  young  child  with  a  complete  cleft, 
it  will  be  noticed   that  the  ui)per  alveolar  ridge  is  immediately  over 


346  RELATION  OF  THE  TWO  JAWS 

the  alveolar  ridge  of  the  lower  jaw,  or  it  may  be  external  to  it;  in  the 
normal  child  or  in  the  person  of  advanced  age  the  upper  alveolar  ridge 
is  in  vertical  line  within  that  of  the  lower  jaw,  as  is  w^ell  illustrated  in 
Figs.  196  and  372  and  in  Figs.  375  and  376. 

Congenital  cleft  palate  has  also  been  attributed  to  the  effects  of 
s^^philis  during  intra-uterine  life.     (Hopewell-Smith.) 

Manner  of  Drinking. — Individuals  having  cleft  palate,  especially 
those  with  double  cleft,  have  not  the  power  to  drink  when  the  anterior 
portion  of  the  mouth  is  on  a  lower  level  than  the  posterior  portion. 
The}'  are  compelled  to  raise  the  head,  thus  throwing  the  fluid  back 
into  the  pharynx,  similar  to  the  manner  in  which  a  chicken  drinks. 
This  mode  of  drinking  is  normal  with  the  chicken,  as  it  has  naturally 
a  cleft  palate,  and  has  not  the  power  of  suction  as  performed  in  man 
by  the  glossopalatinus  muscle.  A  child  with  a  complete  cleft  has  no 
power  of  suction  with  the  lips,  but  if  an  artificial  nipple  be  long  and 
large,  the  child  may  seize  it  with  the  palatal  muscles,  which  will  give 
the  power  of  sucking  or  of  drawing  the  fluid  through  the  nipple.^ 

Mold  upon  which  the  Maxilla  is  Formed. — It  is  generally  accepted 
that  the  lower  jaw  acts  as  a  matrix  or  mold  upon  which  the  upper  jaw 
is  formed.  To  an  extent  it  certainly  becomes  the  mold  upon  which 
the  inferior  border  of  the  upper  jaw  is  formed,  as  the  latter  comes  in 
contact  with  its  inner  edges.  This  action  also  influences  the  general 
contour  and  shape  of  the  superior  alveolar  ridge  and  roof  of  the  mouth. 

Fig.  371  is  a  picture  taken  from  the  skull  of  a  fully  developed  fetus. 
The  skull  has  been  cut  vertically  and  transversely  in  the  region  of  the 
developing  deciduous  teeth  of  both  jaws,  showing  the  jaws  in  trans- 
verse section.  The  skull  is  quite  symmetrical.  It  is  plainly  to  be 
seen  that  the  width  of  the  upper  jaw  is  much  less  than  that  of  the 
lower. 2  As  a  further  evidence  of  this  fact,  if  vertical  lines  are  drawn 
through  the  centres  of  the  tooth-germs  and  the  alveolar  process  of 
each  jaw,  it  will  be  found  that  the  lines  of  the  upper  jaw  are  on  the 
inner  side  of  those  of  the  lower  jaw,  the  extent  of  the  difference  being 
about  one-half  of  the  thickness  of  the  lower  jaw. 

'  Vor  surgical  procedure  and  further  description  of  cleft  palate,  see  Brophy's  Oral  Surgery,  p.  563. 
'  For  description  of  other  features  shown  in  this  illustration,  see  Fig.  195. 


MOLD   L  J'(>.\    WHICH   THE   MAXILLA    IS  LoKMED 


:\A\ 


Fig.  372  is  taken  from  an  adult  jaw.  If  lini's  he  drawn  through  the 
longitudinal  axes  of  the  upper  and  the  lower  teeth,  it  will  be  found  that 
those  through  the  former,  as  the}'  extend  toward  the  coronal  surfaces, 
pass  a  little  outward,  while  those  passing  up  through  the  lower  teeth 
incline  inward.  This  is  e\  idence  that  the  relation  found  in  the  fetus 
has  been  continued,  and  that  all  through  the  period  of  growth  of  the 
lower  jaw  and  development  of  its  alveolar  process,  the  latter  has  been 
directed  inward,   while  the  upper  aKeolar  j)rocess  has  extended  out- 


Anterior  fossa  of 

brain-case 
Crista  galli 

Orbit 

Medial  wall  of 
nasal  ca\nty 
Ostium  ma.xillare 
Maxillary  sinus 
Zygoma 
^i  axilla 


■  Dental  germs 


Mandible 


Fig.  371. — Vertical  tran.sversc  section  through  the  orbits,  the  nasal  cavity,  and  the  premolar  teeth. 

wardly,  so  that  the  cusps  of  the  upper  permanent  teeth,  when  fully 
developed  normally,  bite  over  the  outer  cusps  of  the  lower  teeth  occlud- 
ing with  them.  If  the  teeth  and  alveolar  process  be  excluded,  it  will 
be  observed,  as  in  the  fetal  skull,  that  the  upper  jaw  is  much  smaller 
than  the  lower. 

FiS-  373  is  from  the  anterior  section  of  Fig.  372.  It  illustrates  the 
occlusion  of  the  anterior  teeth,  also  shows  the  cortical  and  the  cancel- 
lated tissue  of  the  mandible. 


348 


RELATION  OF  THE  TWO  JAWS 


The  Resorption  of  the  Alveolar  Process. — As  the  alveolar  process 
belongs  to  the  teeth  and  is  developed  with  them,  and  its  function  is 
that  of  holding  them  in  position,  it  disappears  to  a  greater  or  less  extent 
after  the  teeth  are  lost.    Hopewell-Smith  has  shown  that  this  resorption 


Fig.  372. — Anterior  view  of  a  vertical  transverse  section  through  the  lower  jaw  and  the  lower 

portion  of  the  upper  jaw. 


P'lG.  373. — Anleri(jr  section  of  Fig.  372. 

of  bone  may  begin  at  a  very  early  age — on  account  of  the  fact  that, 
histologically,  the  structure  of  the  osseous  tissue  differs  considerably 
from  that  found  elsewhere,  and  its  bIo(xl  supply  is  very  inadequate. 

The  manner  of  its  resorption  differs  in  the  two  jaws.     In  the  upper 
the  external  plate  disappears  more  rapidly  than  the  internal,   which 


KI-.LATIOXS  I\   EXT  RUM  li  OLD  ACE  349 

persists  for  a  coiisidt'iaMN  loiiiici-  period.  thoii;<h  in  cxlrcnu'  old  aj^e  tlu' 
entire  process  is  lost,  leaving  a  ver\  narrow  jaw  and  a  small  roof  lo 
the  mouth  (see  I'^igs.  375  and  377). 

In  the  lower  jaw  the  resorption  of  the  two  i)lates  takes  j^lace  more 
evenl\  .  I'suallN  tlie\-  are  resorbed  in  such  a  manner  that  a  slight  ridge 
is  left  between  the  i)laces  which  the>'  formerly  occupied. 

The  Relations  in  Extreme  Old  Age. — As  a  result,  there  is  i)roduced 
a  twofold  effect  upon  the  relation  of  the  jaws.  As  the  resorption  (jf 
the  alveolar  process  goes  on,  the  vertical  distance  between  the  body 
i){  the  lower  jaw  and  that  of  the  upi)er  is  lessened,  while  the  natural 
difference  in  their  width  is  increased.  The  area  of  the  upjKT  jaw 
becomes  smaller  in  proportion  to  that  of  the  lower,  the  axes  of  the 
mandible  extending  further  outward.  In  the  endeavor  to  close  the 
jaws  imder  these  circumstances,  the  lower  is  projected  further  forward 
as  it  rises  to  meet  the  upper,  until,  in  extreme  cases,  it  may  pass  abso- 
lutely outside  of  the  upper.  This  is  a  frequent  characteristic  of  the 
edentulous  jaw  in  old  age. 

If  properly  fitting  artificial  dentures  are  placed  in  the  mouth 
l)romi)tly  after  the  loss  of  the  natural  teeth,  the  resorption  of  the 
alveolar  process,  and  particularly  the  change  in  the  angle  of  the  jaw, 
will  be  retarded.  Thus,  if  these  teeth  are  replaced  from  time  to  time 
by  dentures  adjusted  to  the  conditions  as  the  processes  recede,  this 
characteristic  change  of  old  age  will  be  overcome  to  a  very  large  extent. 

Figs.  374  and  375  are  taken  from  two  skulls  of  alxjut  the  same 
shape  and  size.  Fig.  374  is  from  an  adult  of  about  twenty-fi\e  years, 
having  a  full  series  of  normally  occluded  teeth.  The  direction  of  the 
upper  and  lower  teeth  can  be  observed  as  described.  Fig.  375  is  from 
a  person  of  seventy-five  years  or  more,  where  all  the  teeth  were  lost 
and  the  alveolar  process  resorbed,  showing  the  upper  and  lower  jaws  in 
their  normal  shape  and  relations. 

Fi^s.  376  and  377  are  a  side  view  of  the  same  skulls  shown  in  Figs. 
374  and  375.  It  seems  evident  from  these  skulls,  which  are  typical 
and  not  exceptional,  that  if  the  teeth  be  lost  and  the  alveolar  ])rocess 
resorbed  after  middle  life,  the  upper  and  lower  jaws  cannot  be  again 
brought  into  occlusion  through  their  aKeolar  borders. 


350 


RELATION  OF  THE  TWO  JAWS 


Causes    of    Malformation    of   the   Jaws. — The   normal    action   and 
reaction  between  the  two  jaws  has  been  spoken  of  as  producing  irregu- 


FiG.  374  Fig.  375 

Figs.  374  and  375. — Two  adult  skulls  viewed  from  below:    Fig.  374  from  a  subject  about  twenty 
3'ears  old;  Fig.  .375  from  one  well  advanced  in  years. 


Fig.  376  Fig.  377 

Figs.  376  and  377. — Side  view  of  the  two  skulls  shown  in  F"igs.  374  and  375. 

larities  in  the  shape  of  the  arches,  of  the  roof  of  the  mouth,  and  in  the 
position  of  the  teeth.     In  general,  it  may  be  said  that  any  cause  which 


CAUSES  OF  MAU'ORM Alios  OF   TIIF  JAWS  W'A 

prevents  the  normal  occlusion  of  the  jaws,  during  either  rest,  speech, 
or  mastication,  will  bring  al)out  malformation  of  these  i)arts.  Among 
the  causes  which  prevent  the  normal  bringing  t(jgether  of  the  jaws  may 
be  mentioned  abnormal  mouth-breathing,  inflammation  of  the  bone, 
of  its  periosteum  or  of  the  pericementum,  or  conditions  causing  pain 
when  the  teeth  come  in  contact.  Abnormal  mouth-breathing  sh(juld 
be  corrected,  whether  it  is  caused  by  bony  obstruction,  in  hypertrophy 
of  the  mucous  membrane,  or  by  adenoid  growths  in  or  about  the  naso- 
phanngeal  space  or  by  narrow  dental  arches.  While  the  jaws  are! 
kept  apart  the  muscles  in  connection  with  the  orbicularis  oris  are  some-l 
what  tightened,  and  a  pressure  which  has  a  tendency  to  force  the  teeth 
inward  is  brought  to  bear  upon  the  non-occluding  teeth,  causing  mal- 
occlusion. While  this  feature  has  received  very  general  acceptance, 
it  is,  in  the  opinion  of  the  writer,  merely  an  incidental  factor,  and  (.A 
far  less  etiological  significance  than  the  loss  of  the  developing  and 
molding  influence  which  directly  results  from  the  percussive  force 
of  occlusion  exerted  by  the  mandible  upon  the  maxillary  arch.  The 
presence  of  adenoid  growths  in  the  nasopharynx,  or  in  fact  ain-  cause 
which  interferes  with  the  normal  closing  of  the  mouth,  at  once  interferes 
with  occlusion,  which,  in  view  of  more  recent  studies,  the  writer  regards 
as  the  most  potent  factor  in  the  normal  development  of  the  relation 
of  the  upper  to  the  lower  dentures. 

It  is,  of  course,  to  be  understood  that  the  factor  behind  these 
anatomical  variations,  leading  to  asymmetrical  development,  is  neces- 
sarily that  of  nutrition.  Some  interference  with  local  nutrition  has 
brought  about  functional  disturbance  of  a  part,  and  this,  in  turn,  a 
corresponding  modification  of  anatomical  form. 

The  writer  in  conclusion  suggests  that  the  data  which  are  embodied 
in  this  work  will  not  be  regarded  as  exhaustive  of  the  subject,  but 
rather  as  an  indication  of  the  magnitude  of  the  field  to  be  studied, 
and  more  particularly  as  suggestive  of  the  rational  method  by  which 
the    subject    should    be    investigated. 


I  NDEX. 


Abscesses,  238-24 1,  209 
Acoustic  meatus,  73 
Alignment  of  teeth,  120,  121 
Alveolar       process,       anteroposterior       section 
through,  128 
hypertrophy  of,  342 
of  mandible,  25,  77 
resorption  of,  271,  348 
Anatomical  structures,  20 

variations  in,  263-284 
Anatomy,  263 

Anesthesia,  local,  of  parts  of  face  controlled  by 
the  trigeminal  nerve,  163-165 
of  teeth,  163-165 
Ankylosis,  action  of  depressor  muscles  of  man- 
dible. 337 
false,  330 

treatment  of,  331,  3^2,  333 
of  mandible,  changes  in,  333 
typical,  332 
unilateral,  334 
true,  335 
Antrum  of  Highmore,  217 
Arter\-,  inferior  alveolar,  135 
internal  maxillary,  135,  138 
superior  alveolar,  134 
Articular  tubercle,  loss  of,  337 
Articulation  of  mandible,  70 

changes  in,  337,  338,  339,  340 
Auditory  tubes,  196,  206 
Auriculotemporal  nerve,  150 

branches  of,  150,  151 
Australian,  skull  of,  314 


B 

Badger,  sagittal  section  of  skull  of,  27 1 

Barton's  bandage  in  fractures  of  the  mandible,  60 

Base  of  skulls,  measurement  of,  88 

Body  of  mandible,  description  of,  23 

Bone,  effect  of  hydrogen  peroxide  on,  55 

growth  of,  50 

necrosis  of,  52 

phosphorous,  56 

regeneration  of,  52,  57,  58 

tubercular,  52 
23 


Buccal  cavity,  100 
Buccinator  nerve,  149 

branches  of,  150 
Bulla  ethmoidalis,  pathological  condition  of,  208, 
210,  260 


Calcum,  deposit  of  salts  of,  120,  167,  304 
Cancellated  tissue,  arrangement  of,  in  jaws,  20, 

33,  123 
Canine  teeth,  impacted,  176,  177,  178,  179,  1^0 
mandibular,  111 
crown  of.  111 

anterior  face  of,  112 
cutting  edge  of,  112 
labial  face  of,  1 1 1 
lingual  face  of,  112 
posterior  face  of,  112 
definition  of,  111 
neck  of,  112 
root  of,  112 
maxillary,  105 

crown  of,  105 

anterior  face  of,  106 
cutting  edge  of,  106 
labial  face  of,  105 
palatal  face  of,  105 
posterior  face  of,  106 
definition  of,  105 
neck  of,  106 
pulp  of,  106 
root  of,  106 
Caucasian  mandible,  328 

skull,  84,  310 
Cell  of  orbital  process,  207.  232,  233,_  235 
Child's  head,  transverse  section  of,  95 
Chinese  mandible.  30 
skull,  87 

measurement  of,  88,  92 
Ciliary  ganglion,  155 

branches  of.  155,  156 
Cleft  palate,  80,  345,  346 
Concha,  middle  inferior,  291 
superior,  204,  224 
sphenoid,  262 
Condyloid  process,  69 
Cribriform  tube,  dental  branches  of,  37 


354 


INDEX 


Cribriform  tube  of  mandible,  ii,  34 
Crista  galli,  cell  of,  251,  262,  275,  276 

variations  of,  264-284 
Crown  of  first  mandibular  molar  teeth,  114 

maxillary  molar  teeth,  108 
of  mandibular  canine  teeth,  111 

incisors,  111 

premolar  teeth,  112 
of  maxillary  canine  teeth,  105 

incisors,  104 

premolar  teeth,  106 
of  second  mandibular  molar  teeth,  115 

maxillary  molar  teeth,  109 
of  third  mandibular  molar  teeth,  116 

maxillary  molar  teeth,  109 
tooth,  definition  of,  103 
Cysts,  dental,  193,  213 

pathology  of,  193 

x-rays  in  diagnosis  of,  193,  195 
dentigerous,  193 
in  impacted  teeth,  193 


Deciduous  teeth,  102,  103,  117,  171,  172 
pathological  effects,  120 
relations  with  permanent  teeth,  172 
Deep  temporal  nerve,  148 
Dental  arch,  94 

narrow,  94,  96,  97,  120,  269,  296 
variations  of,  264-284 
wide,  96,  97 
cysts,  193 

diagnosis  of,  x-rays  in,  193 
pathology  of,  193 
Dentition,  prehensile  type  of,  312 
Deposit  of  salts  of  calcium,  304 
in  early  life,  304 
insufficient,  304 
undue,  304 
Depressor  muscles    of    mandible,    action    of,    in 

ankylosis,  337 
Development  of  face,  20 
Diagrams  of  angles  of  mandible,  31 


Egyptian  mandible,  317,  319 

Engine,  surgical,  76 

Epiglottis,  288 

Eruption  of  teeth,  118,  119,  171,  172 

irregular,  influence  on  teeth,  166 

retarded,  166 
Ethmoidal  cells,  204,  205,  207,  235,  259,  291 

anterior,  259 

definition  of,  259 

middle,  260 

posterior,  260 
nerve,  144 


External  pterygoid  nerve,  149 

Extraction,  191 

of  impacted  teeth,  192 
of  teeth,  42,  46,  49,  224 


Face,  anatomical  structures  of,  20 
variations  in,  263 
cancellated  structures  of,  20 
development  of,  21 
internal  anatomy  of,  17 
neuralgia  of,  64 

sections  of  bony  structures  of,  263-284 
sensory  nerve  supply  of,  139 
False  ankylosis,  330 
Fan  tribe,  West  Africa,  mandible  of,  328 

skull  of,  310 
Fifth  nasal  meatus,  208 
First  mandibular  incisors.  111 
molar  teeth,  113 
premolar  teeth,  112 
maxillary  incisors,  104 
molar  teeth,  108 
premolar  teeth,  106 
Five  maxillary  incisors,  322 
Flathead  Indian,  skull  of,  305 
Floor  of  nose,  narrow,  96 

wide,  94,  96 
Foramen,  incisive,  182 
Fourth  meatus  of  Zuckerkandl,  208 

molar  teeth,  impacted,  322 
Fracture  of  mandible,  50,  59 
treatment  of,  60,  61 

Barton's  bandage  in,  60 
interdental  splints  in,  60 
of  neck  of  mandibular  condyle,  60,  62,  63,  70 
Frontal  nerve,  142 

sinus,  203,  206,  212,  248 
development  of,  248 
numerous,  253 
obstruction  of  fluids  in,  215 
occlusion  of  outlets  of,  212 
septa  of,  249-256 
sizG  of   254 

variations  of,  248-258,  276 
Frozen  sections,  285-303 


Ganglion,  ciliary,  155 

otic,  161 

sphenopalatine,  157 

submaxillary,  162 

sympathetic,  154 
Greyhound,  sagittal  section  of  skull  of,  270 
Growth  of  bone,  50,  51 
Gums,  hypertrophy  of,  342 
treatment  of,  343 


IXDKX 


355 


H 


Hard  palate,  100 
Hare-lip,  caiisi-  of,  345,  346 
Head,  analumical  variations  of,  17 

frozen  sections  of,  2.S5-303 

directions  for  niaicin^,  285 
Heavy  nKui(lil)le,  2.S,  315 

skull,  SO 

measurement  of,  88,  92 
Heidelberg  skull,  313 
Hiatus  semilunaris,  207,  210,  291 

variations  of,  264-284 
Highmore,  antrum  of,  217 
Hydrocherus  capybara,  71,  72 
Hydrogen  peroxide  necrosis  of  mandible,  53 
Hypertrophy  of  alveolar  process,  342 

of  gums,  342-344 


Impacted    teeth,    166,     174,     176,     177,     178, 
179 
canine,  causes  of,  167,  173 
c^sts  in,  193 
diagnosis  of,  170,  192 

value  of  .Y-rays  in,  170 
first    mandibular    molar,    absorption  of 

roots  of,  187 
fourth  molar  teeth,  322 
general  effects  of,  170 
incisors,  174,  175,  181 
local  effects  of,  169,  178 
molar,  180,  181,  182 
neuralgia  in,  192 
second  mandibular  molar,  187 

molar  teeth,  316 
in  skull  of  monkey,  168,  169 
supernumerary  tooth,  173,  174,  181 

systemic  effects  of,  172 
third,  mandibular   molar,  171,  183-186, 
188,  189,  190,  191 
extraction  of,  191 
maxillary  molar,  182,  183 
Incisors,  impacted,  174,  175,  181 

due  to  disease  in  nasal  cavity,  192 
mandibular,  HI 
crown  of,  111 

cutting  edge.  111 
labial  face,  1 1 1 
lateral  faces,  1 1 1 
lingual  face,  111 
definition  of.  111 
first,  111 
neck  of,  111 
pulp  of,  111 
root  of,  111 
second.  111 
maxillary,  103 

crowns  of,  103 


Incisors,  maxillary,  crowns  of,  anterior  face  of, 
104 
cervical  margins  of,  104 
cutting  edge  of,  104 
labial  face  of,  103 
palatal  face  of,  104 
posterior  face  of,  104 
proximal  face  of,  104 
definition  of,  103 
first,  104 
neck  of,  104 
pulp  of,  105 
root  of,  104 
second,  104 
Indian,  mandible  of,  27 
Inferior  alveolar  artery,  135 
course  of,  136 
mental  branch  of,  136 
mylohyoid  branch  of,  135 
nerve,  152 

branches  of,  153 
nasal  meatus,  201 
Inflammatory  changes  in  mandible,  48 
of  children,  48 
surgical  pathology  of,  49 
Infraorbital  nerve,  147 

branches  of,  147 
sinus,  228,  272 
Infratrochlear  nerve,  145 
Infundibulum,  291 
Interdental  splints,  60 
Internal  maxillary  artery,  135,  138 
course  of,  135 
maxillary  division  of,  135 
pterygoid  division  of,  135 
pterygopalatine  division  of,  135 
nasal  nerve,  144 
pterygoid  nerve,  149 
Introduction,  17 
Irregular  eruption,  influence  on  teeth,  166 


Jaw,  body  of,  3i 

structure  of,  33 

lower,  23 

upper,  81 

intermaxillary  suture  of,  81 
interpalatal  suture  of,  81 
interpremaxillary  suture  of,  81 
maxillnpremaxillary  suture  of,  81 
palatomaxillary  suture  of,  81 
premaxillae  of,  81 
Jaws,  malformation  of,  causes  of,  350,  351 

modern,  .v-ray  pictures  of,  318,  319 

relations  of,  345 
in  old  age,  349 
variations  of,  345 

x-ray  picture  of.  125,  126.  128,  129,  130 


356 


INDEX 


Lacrimal  nerve,  143 
Lamina  dura,  77 
Lingual  nerve,  151 

branches  of,  151,  152 
Long  ciliary  nerves,  144 


M 


Malformation  of  jaws,  causes  of,  350 
Mandible,  23 

abnormal  position  of  condyle  of,  62 
abnormalities  in  density  of,  65 
alveolar  process  of,  25 

anatomical  arrangement  of,  pathological  sig- 
nificance of,  38,  40 
surgical  significance  of,  38,  42 
angles  of,  30 
ankyloid,  typical,  332 
ankvlosis  of,  action  of  depressor  muscles  in, 

337 
articulation  of,  68 

anatomy  of,  68 

at  birth,  73 

in  carnivora,  71 

changes  in,  72 

in  man,  71 

mechanism  of,  70 
cancellated  structure  of,  43,  44 
cast  of,  45 
Caucasian,  328 
Chinese,  30 
cribriform  tube  of,  34 
cross-sections  of,  41,  42,  46,  47,  49,  65 
dental  branches  of,  37 
development  of,  records  of,  39 
diseased,  sequestrum  of,  59 
Egyptian,  317,  319 
of  Fan  tribe.  West  Africa,  328 
of  flat-faced  person,  30 
fractures  of,  59 
growth  of,  23,  37 
heavy,  28,  315 

hydrogen  peroxide  necrosis  of,  53 
of  Indian,  27 

inflammatory  changes  in,  48 
longitudinal  section  of,  44 
measurements  of,  30 

in  various  ages,  31,  32 

various  types  of,  31 
mental  process  of,  25 
method  of,  growth  of,  37 
necrosis  of,  49,  55 

phosphorous,  54 
prehistoric,  318,  320 
prognathous,  28 
regeneration  of,  49 

of  bone  in,  57,  58 
relation  of,  to  base  of  skull,  124 


Mandible,  .relation   of   condyloid    process  of,  to 
mandibular  fossa,  69 
of  rodents,  72 
secondary  deposits  of,  64 
shape  of,  23 

in  aged  persons,  24 
at  maturity,  24 
of  South  African  negro,  27 
surgical  pathology  of,  38,  42 

of  inflammatory  changes  in,  49 
triangle  of,  67 

variations  in,  67 
tubercular  necrosis  of,  52 
typical,  upper  part  of,  body  of,  122 
U-shaped,  vascular  supply  of,  136 
vascular  supply  of,  136 
of  vertebrates,  72 
Mandibles  of  different  races,  26 

comparison  of,  26,  329 
Mandibular  articulation,  68,  70,  73,  74,  324 
changes  in,  337 

through  loss  of  teeth,  338-341 
canal,  ii 
canine  teeth,  111 
condyle,  neck  of,  fracture  of,  60 
correction  of,  75 
fossa,  relation   of,    to   condyloid    process   of 

mandible,  69,  71,  72 
incisor  teeth,  110 
molar  teeth,  113 
nerve,  147 
premolar  teeth,  112 
teeth,  definition  of,  110,  111 

neck  of,  horizontal  section  of,  126,   127 
Masseteric  nerve,  148 
Maxilla;,  76 

alveolar  process  of,  77 

external  plate  of,  77 
internal  plate  of,  77 
architectural  features  of, 76 
definition  of,  76 
mold  for  formation  of,  346 
pathological  relations  of,  77 
vascular  supply  of,  135 
Maxillary  alveolar  nerve,  distribution  of,  140 
canine  teeth,  105 
incisors,  103 
five,  322 
molar  teeth,  107 
nerve,  145 

branches  of,  146 
premolar  teeth,  106 
sinus,  94,  128,  129,  217 
anterior  wall  of,  225 
anteroposterior  section  through,  128 
dental  relationships  of,  235 
descriptive  anatomy  of,  217 
development  of,  219 
floor  of,  223 

impacted  tooth  in,  178 
infection  from  teeth,  236-242 


I.XDKX 


Maxillary  sinus.  larj;e,  98,  22.^ 
nas<il  wall  of,  227 
outer  wall  of,  226 
out  1ft,  244 

patholo^jical    conditions   of,    2.^7,     244, 
245 
treatment  of,  246,  247 
posterior  wall  of,  226 
proximal  wall  of,  227 
roof  of,  226 
septa  of,  227-234 
small.  99 

superior  wall  of,  226 
surgical  relations  of,  242 
typical,  221 

variations  of,  223,  264-284 
A-rayof.  222 
zygomatic  wall  of,  226 
Maxillomandibular  splints,  60 
Mental  foramen,  36 
process.  25.  26 

function  of.  26 
Mesa  X'crde  Indian,  skull  of,  306-309 
Middle  nasal  meatus,  196,  205 
Mixed  race,  skull  of,  85 

measurements  of,  88 
Modification  of  the  normal   shape  of  the  bone 
through  abnormal  forces,  304 
of  skulls  by  age,  climate,  diet,  occupation, 
18 
bv  artificial  means,  305-309 
Molar  teeth,  impacted,  125,  180-190 

second  mandibular,  187,  315 
third  mandibular,  183-190 
mandibular,  113 

definition  of,  113 
first,  113 

crown  of,  114 

anterior  face  of.  114 
buccal  face  of.  1 14 
morsal  face  of,  1 14 
palatal  face  of,  1 14 
posterior  face  of,  1 14 
neck  of,  114  , 

roots  of,  115  i 

second,  115 

crown  of,  115  I 

anterior  face  of,  115 
buccal  face  of,  115 
morsal  face  of,  115 
palatal  face  of,  115 
posterior  face  of,  115 
neck  of,  115 
pulp  of,  116 
roots  of,  116 
third,  116  '■ 

crown  of,  1 16  j 

faces  of,  116  | 

neck  of,  116  < 

roots  of,  116  ' 

maxillary,  107  i 


Molar  teeth,  maxillary,  definition  of,  107 
first,  108 

crown  of,  108 

anterior  face  of,  109 
buccal  face  of,  108 
morsal  face  of,  109 
palatal  face  of,  109 
jKJsterior  face  nf,  109 
neck  of,  109 
roots  of,  109 
second,  109 

crown  of,  109 

anterior  face  of,  110 
buccal  face  of,  109 
palatal  face  of,  109 
posterior  face  of,  110 
neck  of,  110 
roots  of.  110 
third,  110 

description  of,  110 
rudimentary,  .^\2-~^22 
suppressed,  312-322 
Monkey's  skull,  impacted  teeth  in,  168,  169 
Mouth,  100 

anatomy  of,  100,  101 
asymmetrical  arch  of,  263 
functions  of,  100 
interpalatal  suture  of,  78 
interpremaxillary  suture  of,  78 
position  of,  100 

relation  of,  to  nasal  chamber,  285-303 
to  pharynx,  285-303 
to  tongue,  285-303 
roof  of,  100 
sides  of,  101 

sutures  of  the  roof  of,  78 
vestibule  of,  100 
Muscles  of  mastication,  changes  in,  300,  337 
corrugator,  142, 
frontalis,  142 
obicularis  oris,  142 
pterygoideus  externus,  70,  159 
Muscular  action,  influences  of,  on  skull,  330 


N 


Nasal  cavity,  196,  203 

descriptive  anatomv  of,  196 

floor  of,  197 

fluids  of,  215,  288 

infection  from,  218 

inner  walls  of,  197 

middle  meatus  of,  196,  205 

narrow.  96,  97,  98.  277 

outer  walls  of.  197 

pathological  condition  of.  208 

relation  to  mouth,  285-303 
to  pharynx,  120,  285-303 
to  tongue,  285-303 

roof  of,  197 


358 


INDEX 


Nasal  cavity,  variations  of,  264-284 

wide,  96,  99,  277 
fossa,  94 
meatus,  fifth,  208 

fourth,  275,  277 

inferior,  199,  201,  204 

middle,  205 

superior,  207,  208,  Hi 
meati,  198,  200 
medial  wall,  202 
septum,  198,  290 

spurs  of,  198,  280,  290 

variations  of,  264-284 
Nasociliary  nerve,  143 

branches  of,  143 
Nasolacrimal  canals,  201 

duct,  196,  202 
Neck  of  first  mandibular  molar  teeth,  114 

maxillary  molar  teeth,  109 
of  mandibular  canine  teeth,  112 

incisors.  111 

premolar  teeth,  113 
of  maxillary  canine  teeth,  106 

incisors,  104 

premolar  teeth,  107 
of  second  mandibular  molar  teeth,  115 

maxillary  molar  teeth,  110 
of  third  mandibular  molar  teeth,  116 
of  tooth,  definition  of,  103 
Necrosis  of  mandible,  49,  52 

hydrogen  peroxide,  53,  55 

phosphorous,  54,  56 
tubercular,  of  mandible,  52 
Negro,  skull  of,  314 
Nerve,  auriculotemporal,  150 
buccinator,  149 
deep  temporal,  148 
ethmoidal,  144 
external  pterygoid,  149 
frontal,  142 

inferior  alveolar,  152,  154 
infraorbital,  147 
infratrochlear,  145 
internal  nasal,  144 

pterj'goid,  149 
lacrimal,  140,  143 
lingual,  151 
long  ciliary,  144 
malar,  or  zygomaticofacial,  146 
mandibular,  147,  157 
masseteric,  148 
maxillary,  141,  145 
mental  branches,  154 
nasociliary,  140,  143 
nasopalatine  branch,  160 
ophthalmic,  141 
orbital,  158 
palatine  branches,  159 
pharyngeal  or  pterygopalatine,  160 
posterior  ethmoidal,  144 
spheno-ethmoidal,  144 


Nerve,  superior  alveolar,  146 

supraorbital,  142 

supratrochlear,  142 

trigeminal,  139 

zygomatic,  146 

zygomaticotemporal,  146 
Neuralgia,  facial,  64 

in  impacted  teeth,  169,  175,  186,  189 


O 


Occlusion,  74,  124,  341,  348 
Odontomes,  132,  174 
Ophthalmic  nerve,  141 
Orbicularis  oris,  26,  142 
Orbital  processes,  260 
Osteomyelitis,  245 
Ostium  maxillare,  207,  227 

variations  of,  264-284 
Otic  ganglion,  161 

branches  of,  162 


Palate,  cleft,  346 

manner  of  drinking  in,  346 
hard,  100,  293 
mucoperiosteum  of,  101 
soft,  100,  296 
Periosteum,  50 
Permanent  teeth,  102, 103 
anatomy  of,  103 
Pharyngeal  dome,  height  of,  89 

of  skulls,  measurement  of,  88 
Pharynx,  relation  to  mouth,  285-303 
to  nasal  chamber,  285-303 
to  tongue,  285-303 
Phosphorous  necrosis  of  mandible,  54 
Posterior  ethmoidal  nerve,  144 
Prehensile  type  of  dentition,  312 
Prehistoric  mandible,  318,  320 
skulls,  305-309 

measurement  of,  88,  92 
Premaxillce,  non-union  of,  79 
Premolar  teeth,  mandibular,  112 
crown  of,  112 

buccal  face  of,  112 
lateral  face  of,  112 
lingual  face  of,  112 
morsal  face  of,  112 
definition  of,  112 
first,  112 
neck  of,  113 
pulp  of,  113 
root  of,  113 
second, 112 
maxillary,  106 
crown  of,  106 

anterior  face  of,  107 


IXDEX 


359 


Premolar  tirth,  m.i\illar\-,  cnjwii  of,  l)urcal  face 
of,  UK) 
niorsal  face  of,  107 
palatal  face  of,  107 
posterior  face  of,  107 
definition  of,  lOf) 
first,  100 
neck  of,  107 
pnlj)  of,  107 
root  of,  107 
second,  107 
misplaced,  93 
supernumerary,  323-v329 

.v-ray  picture  of,  324,  325 
Prognathous  mandible,  28 

skull,  measurement  of,  88,  00,  91 
Pulp  of  mandibular  incisors.  111 
premolar  teeth,  1 13 
maxillary  canine  teeth,  106 
incisors,  105 
premolar  teeth,  107 
second  mandibular  molar  teeth,  116 
tooth,  definition  of,  103 


Regexeratiox  of  bone,  49,  50,  51 

of  mandible,  49,  57,  58 
Relation  of  the  two  jaws,  345,  346 
Resorption  of  the  alveolar  process,  348,  349 
Retarded  eruption,  166 
Roots  of  first  mandibular  molar  teeth,  115 
maxillary  molar  teeth,  109 
mandibular  canine  teeth,  112 
incisors.  111 
premolar  teeth,  113 
maxillary  canine  teeth,  106 
incisors,  104 
premolar  teeth^  107 
second  mandibular  molar  teeth,  116 

maxillary -jiiolar  teeth,  110 
third  mandibular  molar  teeth,  116 
tooth,  definition  of,  103 
Rudimentary  molar  teeth,  i\l-il2 


Second  mandibular  incisors.  111 

molar  teeth,  115 

premolar  teeth,  1 12 
maxillary  incisors,  104 

molar  teeth,  109 

premolar  teeth,  107 
molar  teeth,  impacted,  316 
Secondary  deposits,  64 
Sensation,  reestablishment  of,  56 
Sensory  nerve  supply  of  teeth  ami  face,  139 
Sequestrum  of  diseased  mandible,  59 


Skull,  aiUerolateral  \  iew  <jf,  83 
asymmetry  of,  19 
of  badv^er,  sagittal  section  (jf,  271 
base  of.  90,  91,  92,  93 

measurements  of,  88 
belonging  to  mix"  I  race,  85 
brachycephalic,  309 
Caucasian,  84,  310 
Chinese,  87 

composite  picture  of,  311 
external  surfaces  of,  81 
of  Fan  tribe.  West  Africa,  310 
of  Flathead  Indian,  305 
front  view  of,  81 

of  greyhound,  sagittal  section  of,  270 
heax-A',  86 
Heidelberg,  313 

influence  of  muscular  action  on,  330 
measurement  of  base  and  pharvngeal    dome 

of,  88 
Mesa  Verde  Indian,  306-309 
modifications  of,  18 
by  age,  18 

by  artificial  means,  305-309 
by  climate,  18 

diagnostic  importance  of,  19 
by  diet,  18 
by  disease,  18 
of    normal    shape,    through    abnormal 

forces,  304 
by  occujwtion,  18 
of  monkey,  impacted  teeth  in,  168,  169 
narrow,  frozen  section  of,  299,  300 
of  native  Australian,  314 
of  negro,  314 

pharyngeal  dome  of,  measurements  of,  89 
prehistoric,  305-309 
side  view  of,  84 
Sussex,  313 

symmetrical,  frozen  section  of,  298 
symmetrv  of,  81,  83 
typical,  S2,  84,  90,  95 

anterior  portion  of  base  of,  121 
transverse  section  of,  95 
variations  in  shape  of,  causes  of,  304 
West  African,  85 
with  misplaced  premolars,  93 
Skulls,  comparison  of,  311 

of  various  races,  305-314 
Soft  palate,  100 

South  African  negro,  mandible  of,  27 
Sphenoethmoidal  nerve,  144 
Sphenoidal  sinuses,  234,  257,  260 
Sphenopalatine  ganglion,  153,  157 

branches  of,  158,  159,  160 
Splints,  interdental,  in  fracture  of  the  mandible, 
60 
maxillomandibular,  in   fracture  of  the  man- 
dible, 60 
Submaxillary  ganglion,  162 
branches  of,  162 


360 


IXDEX 


Superior  alveolar  nerve,  146 

meatus  of  Zuckerkandl,  208 
nasal  meatus,  207,  208 
Supernumerary-   premolar   teeth,    323-329 
teeth,  173 

impacted,  181 
Suppressed  molar  teeth,  312-322 
Supraorbital  nerve,  142 
Supratrochlear  nerve,  142 
Sussex  skull,  313 

Sutures  of  roof  of  mouth,  78,  80,  81 
intermaxillary,  81 
interpalatal,  81 
interpremaxillary,  81 
maxillopremaxillary,  81 
median  palatal,  78 
palatomaxillary,  81 
Sympathetic  ganglia  connected    with    trigeminal 
nerve,  154,  156 


Teeth,  101 

abnormal,  125,  132,  133 
anatomy  of,  101,  166 
anteroposterior  section  through,  128 
deciduous,  102,  103,  117,  171,  172 

shedding  of,  119 
devitalized,  66,  137 
eruption  of,  118,  172 
functions  of,  102 
fusions  in,  132,  133 

impacted,  125,  128,  129,  166,  169,  324 
influence  of  irregular  eruption  on,  166 
irregularities  in,  132,  133 
local  anesthesia  of,  163-165 
mandibular,  110,  115 

canines.  111 

incisors,  110 

molars,  113,  116 

premolars,  112 
maxillary  canines,  105 

incisors,  103 

molars,  107 

premolars,  106 
nomenclature  of,  102 
occlusion  of,  122 
peculiarities  of,  131,  132,  133 
permanent,  anatomy  of,  103 

set,  102,  103 
pulp  chamber  of,  127 
sensory  nerve  supply  of,  139 
supernumerary,  173 
vascular  supply  of,  134 


Third  mandibular  molar  teeth,  116 

maxillary  molar  teeth,  110 
Tongue,  relation  to  mouth,  285-303 

to  nasal  chamber,  120,  285-303 
to  pharynx,  285-303 
Tooth,  crown  of,  definition  of,  103 
neck  of,  definition  of,  103 
pulp  of,  definition  of,  103 
root  of,  definition  of,  103 
Transverse  sections  of  face,  218,  220,  221,  225, 

229,  277,  279,  280,  281,  282,  283 
Trigeminal  nerve,  139,  243 

course  of,  139 
True  ankylosis,  335 
Tubercular  necrosis  of  mandible,  52 
Typical  skull,  measurement  of,  88,  90 


U 


U-SHAPED  cortical  structure  of  mandible,  33 
Uvula,  293,  295 


Vascular  supply  of  mandibular  teeth,  136 

maxillary  teeth,  135 
Vestibule  of  mouth,  100 


W 


West  African  skull,  85 


X-RAYS  in  diagnosis  of  dental  cvsts,  193 

of  impacted  teeth,  179,  180,  184,  187, 
191,  316,  321,  322 
of  maxillary  sinus,  222 
showing  eight  mandibular  molars,  317,  318 

four  premolars,  325 
of  sinuses,  222,  224 

of  teeth,  125,  126,  128,   129,  130,  169,  170, 
324,  325 


Zygomatic  arch,  84 
bone,  84 
process,  76 


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